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  • 1985-1989
  • 1970-1974  (207)
  • 1950-1954
  • 1972  (207)
  • Ultrastructure  (115)
  • Atomic, Molecular and Optical Physics  (92)
Material
Years
  • 1985-1989
  • 1970-1974  (207)
  • 1950-1954
Year
  • 101
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 132 (1972), S. 431-450 
    ISSN: 1432-0878
    Keywords: Organ of bellonci (Anaspides tasmaniae) ; Crustacea ; SPX organ ; Receptor ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The organ of Bellonci of Anaspides tasmaniae (Thomson) (Crustacea, Syncarida) is described light and electron microscopically, and a few histochemical tests are reported. Located ventrally in the eyestalk below the medulla interna, the organ is composed of a number of cavities. These are similar in structure in their contents and associated cellular components, which include two types of glia cells delimiting each cavity and the terminal parts of a few dendrites. Each dendrite usually bears two cilia, which project into the cavity where they split up into numerous branches. The organ is supplied by three nerve tracts: two from the medulla terminalis and one from the medulla interna. The sensory pore, which is innervated from the medulla interna, is not closely associated with the organ of Bellonci in Anaspides. No marked secretory activity is detectable by histochemical or ultrastructural observations. It is thought that the organ has a sensory function.
    Type of Medium: Electronic Resource
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  • 102
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 133 (1972), S. 59-86 
    ISSN: 1432-0878
    Keywords: Compound eyes ; Coleoptera ; Ultrastructure ; Dark-light-adaptation ; Irregularities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structures of the eyes of two Staphylinid beetles, one large (Creophilus erythrocephalus—18 mm in length) and one small (Sartallus signatus—3 mm in length), were compared. 1. The gross structure of the two eyes is the same: a) biconvex corneal lens, b) crystalline cone of “acone type”, c) narrow crystalline thread and thickening of cone cell extensions just above the rhabdom, d) seven retinula cells plus one basal cell, and e) almost the same corneal refractive index and optical properties of the corneal cuticle. Considerable differences exist in size, shape and arrangement of rhabdom, retinula cells and their axons. The smaller size of the eye of Sartallus is caused by reduction of number of facets rather than cell size, and, in fact, retinula cells and rhabdom have been found to be larger in the smaller beetle. 2. Structural changes during dark-light-adaptation affect crystalline cone, position of screening pigment and size of intercellular spaces between the retinula cells. In the dark-adapted state the cone retracts a little and the crystalline tract becomes wider. A thickening of cone cell extensions occurs just above the rhabdom. Screening pigment migrates to a more distal position and intercellular spaces between the retinula cells considerably increase in size as compared with the light-adapted eye. 3. Both eyes are rich in irregularities. An attempt to classify anomalies of compound eyes has been made. The number of cone cells and principal pigment cells varied, in some cases, from 1–5 and 0–3 respectively. Basal retinula cells did not always contribute to the rhabdom. 4. Interferometrical observations reveal the extreme optical homogeneity of the entire corneal cuticle of the eyes of both species. No layers of different refractive index or optical separation of adjacent ommatidia can be found. The refractive index of the cornea of Creophilus is 1.469; that of Sartallus is 1.488. 5. Functional consequences of the changes which occur during dark-light-adaptation are discussed. Exposure to intense light appears to cause a rapid aging of retinula cells, which is indicated by an increase of onion- and multivesicular bodies.
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  • 103
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 132 (1972), S. 273-285 
    ISSN: 1432-0878
    Keywords: Diplopoda ; Organ of Gabe ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung 1. Das Gabesche Organ von Schizophyllum sabulosum ist paarig und liegt im seitlichen Clypeolabrum. Es wird von Axonen des Nervus labri medialis erreicht, der vorher Seitenzweige abgegeben hat. 2. Die Axone gehören neurosekretorischen Zellen des Protocerebrum an und enthalten Neurosekret. Die Elementargranula sind recht gleichmäßig ellipsoid, der große Durchmesser beträgt ca. 1200 Å. Die Axone enden im Organ und stellen dessen extrinsische Komponente dar. 3. Außerdem gibt es zwei intrinsische Zelltypen: 1) Drüsenparenchymzellen mit axonartigen Fortsätzen und 2) gliaartige Zellen. Die Parenchymzellen bilden Sekret in Form opaker Vakuolen, die deutlich größer als die Neurosekretgranula sind. Auffällig ist das überwiegend vesikuläre endoplasmatische Reticulum. Die Mitochondrien liegen in der Nähe von myelinähnlichen Körpern; ihre Außenmembran ist stellenweise vakuolig vorgewölbt. Die axonartigen Fortsätze enthalten viele längsorientierte Mikrotubuli. 4. Die langen Fortsätze der gliaartigen Zellen umhüllen die Parenchymzellen und die extrinsischen Axone meist in mehreren Schichten. Es gibt aber auch Bereiche, in denen vor allem die Fortsätze der Parenchymzellen und die extrinsischen Axone nackt sind. 5. Das Organ ist gegen das umgebende Hämocoel von einer dicken, lamellierten Stromahülle abgegrenzt. Auch Interzellularräume sind mit Stroma gefüllt. 6. Das Organ wird mit der Cerebraldrüse einiger Chilopoden und gewissen endokrinen Organen anderer Diplopoden und Insekten verglichen.
    Notes: Summary 1. The paired organ of Gabe of Schizophyllum sabulosum is situated in the lateral clypeolabrum. It is innervated by axons of the medial labral nerve, which divides in several branches before reaching the organ. 2. Axons extend from neurosecretory cells of the protocerebrum and contain neurosecretory droplets, which are almost ellipsoid and about 1,200 Å in diameter. The axons terminate in the organ and constitute its extrinsic elements. 3. In addition, there are two types of intrinsic cells: (1) parenchyma cells with axon-like processes and (2) glia-like cells. The parenchyma cells produce secretory material in the form of opaque vacuoles, which are clearly larger than the neurosecretory granules. The preponderantly vesicular endoplasmic reticulum is conspicuous. Also characteristic are the mitochondria, whose superficial membranes are expanded locally, and which lie in the near vicinity of myeline-like bodies. The axon-like processes contain many microtubuli oriented in longitudinal direction. 4. The slender processes of the glia-like cells envelop both parenchyma cells and extrinsic axons usually in several layers; but there are also regions in which the processes of the parenchyma cells and, above all, the extrinsic axons are naked. 5. The organ is delimited from the surrounding hemocoele by a thick laminated stroma. Intercellular spaces are also filled with stroma. 6. The organ is compared with the cerebral gland of some chilopods and with certain endocrine organs of other diplopods and insects.
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  • 104
    ISSN: 1432-0878
    Keywords: Muscle tissue ; Pentastomid ; Body wall ; Parasite ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the body wall muscle of the pentastomid Reighardia sternae is described. The muscle fibres are separated from one another and form two layers, circular and longitudinal. They are cross-striated with approximately 11 actin filaments surrounding each myosin filament. The T-system consists of simple in-pushings of the sarcolemma. The SR is also simple and forms both dyadic and triadic contacts with the T-system tubules and dyadic contacts with the sarcolemma. Electron-dense inclusions occur, usually in the vicinity of the Z-lines, and it is suggested that these may be composed of unsaturated lipids.
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  • 105
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    Cell & tissue research 133 (1972), S. 47-57 
    ISSN: 1432-0878
    Keywords: Endometrium ; Human ; Granular stroma cells ; Relaxin ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'ultrastructure générale des cellules K endométriales est semblable chez l'Homme, le Rat et le Singe. Mais les granulations des cellules K humaines sont plus variées que dans ces deux dernières espèces et ont certains aspects suggérant une fonction catabolique. Etant donné cet aspect catabolique et l'existence connue d'une activité phosphatasique acide de ces cellules contenant de la relaxine, les auteurs suggèrent que les cellules K pourraient être des cellules sécrétantes en involution et ques les cellules sécrétant activement la relaxine pourraient avoir un aspect morphologique quelque peu différent de celui des cellules K.
    Notes: Summary The general ultrastructure of endometrial granular stroma cells is similar in man, rat, and monkey. But the granulations of human granular stroma cells are more various than in these two last species and have some aspects suggesting a catabolic function. With respect to this catabolic aspect and the previously shown acid-phosphatase activity of these relaxin-containing cells the authors suggest that the granular stroma cells could be involutive secretory cells and that the active relaxin-secretory cells may have some different morphological aspect.
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  • 106
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    Springer
    Cell & tissue research 133 (1972), S. 103-118 
    ISSN: 1432-0878
    Keywords: Ovary ; Gastropoda ; Follicle cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Das Ovar von Viviparus contectus besteht, wie licht- und elektronenmikroskopische Untersuchungen ergeben, aus einem langen, terminal verzweigten dünnen Schlauch, dessen Wand von einem Epithel aus Oocyten in allen Entwicklungsstadien und Follikelzellen gebildet wird. Das Vorkommen von Oogonien in den Ovarien adulter Weibchen ist zweifelhaft. Die Follikelzellen sind als Begleitzellen der Oocyten im allgemeinen extrem langgestreckt. Mit ihrer Basis sitzen sie einer dünnen Basalmembran fibrillärer Struktur auf, wie sie bisher nur für Mollusken beschrieben wurde. Die Follikelzellen enthalten große Mengen von Vesikeln, einen bemerkenswert gut ausgebildeten Golgi-Apparat, spärliches rauhes endoplasmatisches Retikulum und zahlreiche heterogene cytosomale Einschlüsse. Charakteristisch für die Zellen sind außerdem in der Längsrichtung liegende cytoplasmatische Mikrotubuli und vereinzelte Kinetosomen. Obwohl keine direkten morphologischen Beziehungen zwischen Follikelzellen und Oocyten festgestellt werden konnten, wird vermutet, daß die Follikelzellen Material degenerierender Oocyten aus dem Lumen des Ovars resorbieren und speichern. Dieses kann den heranwachsenden Oocyten zugute kommen.
    Notes: Summary The ovary of Viviparus contectus was studied light and electron microscopically. It consists of an extended and terminally branched duct, its wall being formed by oocytes of all stages and by follicle cells. The existence of oogonia in the adult females cannot be established with certainty. According to their relationship to the growing oocytes the follicle cells are in general extremely elongated. At the basis they are attached to a thin basement lamina having a fibrillar structure hitherto only known in molluscs. The follicle cells contain many vesicles, a remarkably well-developed golgi apparatus, some rough endoplasmic reticulum, and many heterogeneous cytosomes. Characteristic for these cells are also cytoplasmic microtubules oriented longitudinally along the cell axis. Kinetosomes can rarely be seen. Although there are no apparent direct interrelationships between follicle cells and oocytes, it is suggested that they are engaged in resorbing material of degenerating oocytes from the lumen of the ovary and in storing materials which may be used by the growing oocytes.
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  • 107
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    Cell & tissue research 133 (1972), S. 277-288 
    ISSN: 1432-0878
    Keywords: Flatworm ; Muscle ; Neuromuscular junction ; Sarcoplasm ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neuromuscular junctions in the marine polyclad flatworm, Notoplana acticola were studied with the electron microscope. Synapses were found between nerve endings and specialized extensions of the muscle cells. Characteristically these processes contained clear cytoplasm with a basal mitochondrion and numerous microtubules aligned parallel to the long axis of the extension. Sarcoplasmic diverticuli which contained the nucleus had granular cytoplasm with an assortment of membranes and organelles. We have proposed the term sarconeural junction to describe synapses between long sarcoplasmic extensions and nerve cells in flatworms as well as other animals. Tight junctions between adjacent contractile portions of muscle cells were common. As groups of cells appeared to be connected by tight junctions or shared common nerve terminals we conjectured that these formed discrete functional motor-units.
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  • 108
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 130 (1972), S. 553-574 
    ISSN: 1432-0878
    Keywords: Thyroid gland ; Xenopus laevis ; Iodine uptake ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Ziel dieser Untersuchung war eine physiologische Deutung der Ultrastruktur von Schilddrüsenepithelzellen bei Larven von Xenopus laevis. Dazu wurden elektronenmikroskopische Bilder mit morphometrischen Methoden quantitativ ausgewertet und die Ergebnisse mit Jodaufnahmedaten verglichen. So konnte die Aktivierung der Schilddrüse durch TSH bei kälteblockierten bzw. hypophysektomierten Tieren mit Veränderungen während der spontanen Metamorphose verglichen werden. Ihrer Ultrastruktur nach sind die Schilddrüsen blockierter Prometamorphoselarven in der Entwicklung auf ein früheres Stadium zurückversetzt. Auch zeigen hypophysektomierte Larven keine spontane Jodaufnahme. Eine einmalige TSH-Injektion läßt dann die Größe und Form der verschiedenen Organellen vorübergehend den Zustand der Kontrollen erreichen. Besonders rasch und stark sprechen einerseits die Kernstruktur, andererseits Mikrovilli und Kolloidtropfenvolumen, welche die Resorption von Thyreoglobulin charakterisieren, auf den TSH-Reiz an. Die Jodaufnahme verläuft langsamer. Auch reagieren die an der Synthese beteiligten Organellen später und schwächer. In der spontanen Metamorphose wachsen die Schilddrüsen, nach Totalvolumen, Cytoplasmavolumen einzelner Zellen und Epithelhöhe beurteilt, bis zum Ende der Metamorphose weiter und nehmen entsprechend mehr Jod auf. Ebenso wird während der ganzen Klimax die Kolloidresorption der einzelnen Zellen stärker. Aus den Ergebnissen wird geschlossen, daß die TSH-Sekretion schon in der Prometamorphose einsetzt und bis gegen Ende der Metamorphose zunimmt.
    Notes: Summary The epithelial cells of the thyroid gland in larvae of Xenopus laevis were investigated with the electron microscope. Morphometrical methods yielded quantitative data on the morphology. The uptake of radioactive iodine was studied in order to obtain information on the physiological activity. Thus changes in the thyroid gland following the injection of TSH in tadpoles which had been hypophysectomized or blocked at low temperature were compared with the development of glands during spontaneous metamorphosis. The thyroid glands of blocked prometamorphic larvae resemble those of younger developmental stages as judged by their ultrastructure. In addition no spontaneous accumulation of iodine is observed. Following an injection of TSH the morphology of the various organelles becomes temporarily identical to that of the controls. These changes are most prominent in the nucleus as well as in the microvilli and the colloid droplets, which characterize the resorption of thyroglobulin. Only a minor effect of the TSH stimulus is found on iodine uptake and on organelles concerned with protein synthesis. During normal metamorphosis an increase is observed in the following parameters: (1) volume of the thyroid gland, (2) volume of the cytoplasm and height of single epithelial cells, (3) resorption of colloid, (4) iodine uptake. This increase persists until the end of the climax. Based on the present results TSH secretion is assumed to start in early prometamorphosis and to rise up to the end of metamorphosis.
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  • 109
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    Cell & tissue research 134 (1972), S. 13-30 
    ISSN: 1432-0878
    Keywords: Rat ; Thyroid C-cells ; Ultrastructure ; Tocopherol and Ubiquinone deficiency ; Substitution (d,1-α-Tocopherol, α-Tocopherolquinone)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung An der Schilddrüse von Wistar-Ratten wurde der Einfluß der Kost (Laborstandardkost, halbsynthetische-tocopherolhaltige und halbsynthetische-tocopherol-freie Kost) und der subkutanen Injektion von Tocopherol und Tocopherolchinon auf die Ultrastruktur der C-Zellen untersucht. Während nach Standardfütterung die Aktivität der C-Zellen der Norm entspricht, werden Syntheseleistung und Sekretabgabe dieser Zellelemente durch die halbsynthetische-tocopherolhaltige Kost gesteigert und im alimentären Tocopherol-Ubichinonmangel wieder gedämpft. Der elektronenmikroskopisch erkennbare Gehalt der C-Zellen an Sekretgranula entspricht der in vitro ermittelten Calcitoninaktivität. Die Beziehungen zwischen den Funktionskreisen von Thyreozyten und Calcitoninzellen werden diskutiert.
    Notes: Summary The influence of different diets (standard laboratory diet, semisynthetic tocopherol-containing and semisynthetic tocopherol-free diet) and the influence of subcutaneous injections of tocopherol and tocopherolquinone upon the ultrastructure of the C-cells in the thyroid gland of Wistar rats were investigated. While the activity of the C-cells is quite normal after feeding a standard diet, the synthetic and secretory activities of these cells show an increase with a semisynthetic diet containing tocopherol, but a decrease during alimentary lack of tocopherol and tocopherolquinone. The amount of secretory granules in the C-cells as seen with the electron microscope corresponds with the in vitro-activity of extracted calcitonin. The relations between the functional system of the thyrocytes and that of the C-cells are discussed.
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  • 110
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    Cell & tissue research 134 (1972), S. 539-554 
    ISSN: 1432-0878
    Keywords: Chemoreceptors ; Locusta ; Clypeo-labrum ; Light and electron microscopy ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The A1 sensilla are asymmetric in distribution. Each sensillum contains five bipolar neurons, the distal regions of which extend to the tip of a cuticular cone which has a terminal pore. This was shown with the scanning electron microscope, but was not seen in section. The receptor-lymph cavity of the tormogen cell and the basal cavity of the neurilemma cell contain an electron-dense material unlike other contact chemoreceptors of Locusta prepared for electron microscopy in the same manner. Isolated axons of unknown function occur below the basement membrane and also between epidermal cells surrounding the sensillum.
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  • 111
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    Cell & tissue research 131 (1972), S. 545-557 
    ISSN: 1432-0878
    Keywords: Pars intermedia ; Hypothalamus ; Anurans ; Hormone release ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the pars intermedia of Rana catesbeiana tadpoles was studied following isolation from the hypothalamus, in vivo after sectioning of the pituitary stalk, and in vitro after implantation of the pituitary into a piece of tail fin. Both experimental procedures were followed by rapid and sustained skin darkening. Pituitaries from normal light and dark adapted tadpoles served as controls. In 4-hour disinhibited glands, melanotrophs revealed hyperactive Golgi bodies, colloid vesicles (1–2 microns) in close proximity to axon terminals, and no apparent loss of secretory granules. At 24 hours extracellular colloid adjacent to axon terminals was found, and extensive arrays of RER appeared in the melanotrophs. Obvious granule loss from secretory cells occurred within a week, by which time the cytoplasm was occupied by large cisterns of SER and RER and abundant free ribosomes. Dense core vesicles (600–900 Å) in aminergic nerve terminals disappeared shortly after isolation of the pituitary from the hypothalamus, and only decreasing numbers of translucent vesicles (200–300 Å) were found. The functional significance of these changes is discussed, with particular emphasis on the mode of acute hormone release.
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  • 112
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    Cell & tissue research 135 (1972), S. 115-127 
    ISSN: 1432-0878
    Keywords: Oligodendroglia ; Monkey ; De-afferentation ; Ultrastructure ; Densebodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopical examination of the norma and de-afferented ‘laterall geniculate body’ of the monkey following paraformaldehyde-glutaraldehyde vascular perfusion revealed distinctive morphological features of different types of oligodendrocyte. These cells were normally situated as perineuronal satellites or in relation to axons and capillaries. A wide range of nuclear and cytoplasmic densities were displayed by both satellite and interfascicular oligodendrocytes. The following distinctive features for the identification of ligodendrocytes were utilised: the presence of large quantities of free ribosomes and ribosomal rosettes, microtubular profiles, dense marginal aggregation of nuclear chromatin together with light patches and numerous nuclear pores; but the absence of broad cytoplasmic processes, glycogen and gliofibrils. Circumferential perinuclear organization of the cytoplasmic organelles was typical of oligodendrocytes. Particular attention was paid to perineuronal satellite cells in view of the known transneuronal atrophy in the de-afferented geniculate body. Some cells having a nuclear pattern of oligodendrocytes but showing hyalinisation of perikaryon were seen in de-afferented laminae. A notable feature was the presence of variegated “osmiophilic bodies” in the perikaryon of oligodendrocytes also situated in the de-afferented laminae. A cell type combining the features of oligodendrocytes and astrocytes was classified as ‘intermediate neuroglia’.
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  • 113
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    Cell & tissue research 132 (1972), S. 333-364 
    ISSN: 1432-0878
    Keywords: Pituitary gland ; Amphibians ; Corticotrophs ; Ultrastructure ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé L'identification des cellules responsables de l'élaboration de la corticotropine (ACTH) a été envisagée chezRana esculenta. Les effects causés par l'interrénalectomie au niveau de l'hypophyse ont été étudiés parallèlement par immunofluorescence et au microscope électronique. Au microscope à fluorescence, les cellules détectées chez les animaux témoins avec un antisérum anti-synachten1 bordent en grand nombre les capillaires des zones médiorostrale et ventrale du lobe antérieur. Deux jours après interrénalectomie, le nombre de cellules fluorescentes décroît, douze jours après l'intervention, il ne subsiste pas d'éléments fluorescents dans cette zone. Au microscope électronique, les cellules corticotropes présentent de fines granulations d'environ 200 mμ de diamètre. Après interrénalectomie bilatérale, ces cellules sont fortement stimulées, elles sont sujettes à d'importantes modifications morphologiques; l'aspect morphologique des autres catégories de cellules antéhypophysaires, par contre, n'est pratiquement pas modifié. Douze jours après l'opération, la plupart de ces cellules sont dégranulées, l'ergastoplasme et l'appareil de Golgi sont bien développés. Ces observations suggèrent que les cellules péricapillaires de la moitié rostrale de lapars distalis sécrètent l'hormone corticotrope.
    Notes: Summary Identification of the cell types responsible for the production of adrenocorticotropin (ACTH) was performed inRana esculenta. The effects of interrenalectomy on the pituitary cells were studied as well by immunofluorescence, as by electron microscopy. In control animals, the ACTH cells studied by immunofluorescence are numerous around the blood vessels of the medio-rostral and medio-ventral part of the anterior lobe. Two days after interrenalectomy the number of fluorescent cells decreases. Twelve days after, the operation all the fluorescent cells disappeared. The fine structure of the corticotrophs is characterized by the presence of small secretory granules (200 mμ). After bilateral interrenalectomy this cell type is markedly stimulated; it displays striking morphological changes, while the morphology of the other pituitary cell types is not considerably modified. Twelve days after operation most of these cells are degranulated, the rough endoplasmic reticulum and the Golgi apparatus are well developed. These findings suggest that the pericapillary cells of the rostral half of thepars distalis produce the adrenocorticotrophic hormone.
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  • 114
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    Cell & tissue research 135 (1972), S. 539-551 
    ISSN: 1432-0878
    Keywords: Pseudoculus ; Eosentomon (Protura, Insecta) ; Sense organ ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung In der Feinstruktur unterscheidet sich der Pseudoculus vonEosentomon nicht wesentlich von dem der Acerentomiden. Durch einen Endokutikulaporus treten die dendritischen Fortsätze zweier Sinneszellen, jeweils umgeben von einer Hüllzelle, in den Außenraum des Pseudoculus ein. Der Außenraum wird nach distal von einer äußeren Kutikulaschicht — vermutlich Epikutikula — abgeschlossen. Sie vermittelt durch regelmäßig angeordnete lange Spalten die Verbindung zur Außenwelt. Am Grunde der Spalten finden sich Porentubuli, die mit den Hüllzellen oder den distalen Fortsätzen der Dendriten Kontakt haben können. Aus der Feinstruktur kann geschlossen werden, daß der Pseudoculus als Chemo-, Hygro- und/oder Thermorezeptor fungiert.
    Notes: Summary Concerning its fine structure the pseudoculus of Eosentomon is quite similar to that of Acerentomide Protura. There are two sensory cells innervating the organ. From each of them one dendritic process derives, surrounded by one enveloping cell. The processes of these four cells enter the distal cavity of the pseudoculus through a pore in the endocuticular layer. The cuticular layer of the cap seems to consist of epicuticle only. It is furrowed by long clefts connecting the distal cavity of the organ with the outside. Poretubules insert at the base of the clefts and may have contact with the cell membranes of both enveloping cells and dendritic processes. According to its structure the pseudoculus may function as chemo-, hygro- and/or thermoreceptor.
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  • 115
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    Cell & tissue research 135 (1972), S. 473-482 
    ISSN: 1432-0878
    Keywords: Neurosecretory nerves ; Glial and pigment cells ; Neural sheath ; Gastropods ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of neurosecretory nerves and endings associated with the sheath of the infraesophageal ganglion ofHelix aspersa is described. The sheath is a neurohemal organ whose vascularized stroma receives both monoaminergic and peptidergic endings. The latter occur along the surface of the nerves or scattered within the stroma. They include a complex population of vesicular profiles. The granular vesicles (1300–3000 Å in diameter) exhibit structural modifications that may be related to the intra-axonal release of their neurohormones. The agranular vesicles (500–2000 Å in diameter) occur in large numbers and lie mostly adjacent to the axon surface. Synaptoid specializations seem to represent active sites for the extracellular discharge of neurosecretory material. The monoaminergic endings so far studied lack synaptoid specializations and contain small granular (800–1300 Å in diameter) and agranular (700 Å in diameter) vesicles. Two kinds of non-neural cells are associated with the nerves: glial cells and melanocytes.
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  • 116
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 6 (1972), S. 181-192 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The problem of evaluating the radial electron-electron distribution function P0(r12) from the spin-free 2-particle density matrix P(2)(r1, r2Ir'1, r'2) is considered in detail. The analysis is first applied to 2-electron S-type functions built from l2 configurations. For the special case l = 0, the expression for P0(r12) reduces to the result obtained by Coulson and Neilson.For non-spherically symmetric states of N-electron atoms, the angular integrations are handled by a procedure used by Calais and Löwdin in their evaluation of atomic integrals containing functions of r12. Consideration is also given to the evaluation of necessary radial integrals.
    Additional Material: 2 Tab.
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  • 117
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    International Journal of Quantum Chemistry 6 (1972) 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 118
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    International Journal of Quantum Chemistry 6 (1972), S. 281-287 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A simple semi-theoretical expression for β, the core resonance integral as used in the semi-empirical π-èlectron calculations has been proposed. β's for some standard C = C and C = 0 lengths have been evaluated with the proposed formula and the calculated values are compared with those obtained by other semi-theoretical and empirical methods. Electronic spectra of ethylene, formaldehyde, trans-butadiene and benzene have been calculated by a Pariser-Parr-like semi-empirical method with the values of β thus obtained. The calculated spectra are found to be in good agreement with the observed ones.
    Additional Material: 2 Tab.
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  • 119
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    International Journal of Quantum Chemistry 6 (1972), S. 337-345 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The variation perturbation method in the coupled Hartree-Fock (HF) scheme has been used to calculate the fourth-order energies of He, Li+ and Be2+ ions subjected to a uniform external electric field. The hyper-polarizabilities γh which are related to the fourthorder energies have been calculated neglecting intra-atomic correlation. For He the observed value is γh = 53.6 ± 4.0 a.u. The present estimate in the coupled and uncoupled HF schemes yield 36.2 and 45.3 a.u. respectively. The other calculations using correlated ground state wave function gave values in the range 42-44 a.u. The discrepancies between our result and those of others have been discussed.
    Additional Material: 2 Tab.
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  • 120
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    International Journal of Quantum Chemistry 6 (1972), S. 383-386 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is a standard theorem of group representation theory that the dimension of an irreducible representation is a divisor of the order of the group. This paper gives a new, relatively simple proof, intended to make the theorem understandable to readers unfamiliar with algebraic integers.
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  • 121
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ground and excited singlet state dipole electric π polarizabilities of a set of conjugated molecules are calculated. Second order perturbation theory is used in the Epstein-Nesbet and Möller-Plesset versions. Hückel and SCF-LCAO-MO are used alternatively as a basis. The Möller-Plesset-SCF-LCAO-MO calculation appears well related to experimental values.
    Additional Material: 2 Tab.
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  • 122
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    International Journal of Quantum Chemistry 6 (1972), S. 455-464 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theory for using non-orthogonal radial orbitals between shells with identical orbital quantum numbers, in the case of complex configurations, is presented. Construction of the antisymmetric wave function of the whole configuration, with the help of antisymmetrical wave functions of individual shells, is described. General methods of calculating matrix elements of one- and two-electron operators are given.
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  • 123
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    International Journal of Quantum Chemistry 6 (1972), S. 509-518 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Diatomic integral formulas involving Slater-transform-Preuss functions are obtained for the Coulomb and hybrid types. One-center Coulomb integrals are also considered. All results have finite sums containing a one-dimensional numerical integration.
    Additional Material: 1 Ill.
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  • 124
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    International Journal of Quantum Chemistry 6 (1972), S. 925-933 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown how the irreducible representations of a finite group can be calculated from the irreducible characters (the latter can be calculated exactly by using Dixon's method). All elements of the matrix, representing a group element, lie in the rational field of polynomials of ξ = exp (2πi/e), where e is the exponent of the group.
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  • 125
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    International Journal of Quantum Chemistry 6 (1972), S. 975-988 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The quadrupole moment functions (molecular quadrupole moment versus internuclear distance) have been determined by quantum mechanical calculations for H2 (by Kolos and Wolniewicz), N2 (by Wahl and Nesbet), and CO (by Nesbet). These functions are used with numerical vibrational wave functions to compute matrix elements which are useful for calculations of scattering cross sections, energy transfer rates and excitation probabilities, and infrared intensities of forbidden bands.
    Additional Material: 9 Tab.
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  • 126
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    International Journal of Quantum Chemistry 6 (1972), S. 327-336 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The one-electron Hamiltonian method is developed to solve the variational equations of the MC SCF theory.The many-parameter family of the one-electron Hamiltonian is derived and conditions for parameters to provide convergence of the SCF procedure to the energy minimum are obtained. A computation scheme based on the use of the one-electron Hamiltonian is described.
    Additional Material: 10 Tab.
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  • 127
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    International Journal of Quantum Chemistry 6 (1972), S. 367-382 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The separated electron pair (SEP) model (strongly orthogonal geminals) and methods for its systematic extension have been applied to three different localization schemes for C≡O. The optimum SEP wave function is obtained for the particular localization scheme that involves three equivalent bent bonds. The major corrections to the SEP model arise from one-electron transfer terms. Two-electron transfer terms were important only for those pairs that were not well localized. It was found that the separate definitions of the total intrapair and interpair correlation energies did not depend strongly on the choice of localization scheme.
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  • 128
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    International Journal of Quantum Chemistry 6 (1972), S. 401-406 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ground state single determinant LCAO-MO-SCF wave functions, using a large contracted Gaussian basis set (6s, 2p, 1d/3s, 1p), have been computed for the 9 electron molecular systems of CH3 and NH3+. The minimum energies obtained using Roothaan's open shell SCF procedure for the planar equilibrium geometries were -39.5703 Hartree for CH3 and -55.8945 Hartree for NH3+. Additional properties such as electron populations and multiple moments were calculated from the planar wave functions.
    Additional Material: 1 Ill.
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  • 129
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    International Journal of Quantum Chemistry 6 (1972), S. 449-453 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that under certain conditions the time-dependent Hamilton-Jacobi equation (TDHJE) is satisfied in the mean in quantum mechanics provided the classical action is replaced by Dirac's complex quantal action. This may be regarded as the equivalent of Ehrenfest's theorem for the TDHJE. Expectation values of operators are discussed in a similar manner.
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  • 130
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    International Journal of Quantum Chemistry 6 (1972), S. 501-508 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ground state H—H+ and H—H interactions are used as model interactions for investigating the feasibility of using Gaussian basis sets for representing charge overlap effects in intermolecular forces. The non-expanded charge-induced dipole energy and the non-expanded dipole-dipole dispersion energy, respectively, for these interactions are calculated using two types of Gaussian basis functions to represent the first order wave function, Ψ(1). Very good results for these interaction energies, which include charge overlap effects, are obtained for all interatomic separations by using small Gaussian basis sets to represent the interaction, that is Ψ(1), and/or the isolated atoms (the zeroth order wave function).
    Additional Material: 5 Tab.
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  • 131
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The valence electron distributions of the hydrogen-bonded systems C4H4NH … NC5H5 formed from pyrrole and pyridine and C4H4N- … HNC5H+ from pyrrole anion and pyridinium ion have both been investigated using the charge iterative extended Hückel method. The results are presented in the form of contour diagrams showing the charge densities in pertinent sections of the hydrogen-bonded systems, and also in the corresponding parts of the non-interacting constituent molecules. The density differences between interacting and non-interacting systems brought about by hydrogen bonding are also presented. Like earlier investigated hydrogen bond types, an N—H … N bond is characterized by an increase of charge density in the covalent N—H bond, and a decrease at the acceptor atom. The formation of a rather low maximum in the centre of the H … N bond is also observed. The hydrogen bonding interaction causes a transfer of charge to the donor molecule of the same order of magnitude in both systems considered.
    Additional Material: 7 Ill.
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  • 132
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    International Journal of Quantum Chemistry 6 (1972), S. 555-574 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A self-consistent perturbation theory is derived in the framework of Roothaan's MOLCAO procedure for closed shell systems. Contrary to previous investigations which have considered only one particle perturbations, two particle perturbation operators are considered. Expressions for the first-order density matrix and first- and second-order energy corrections are obtained. A diagram formulation of the complete perturbation expansion is presented.The results are applied to the treatment of the intermolecular interaction problem. The interaction energy is represented as a sum of several contributions: Coulomb, exchange, resonance, polarization and exchange repulsion. A semi-empirical version of the theory is suggested which explicitly involves all the physically significant energy terms and may be useful for the investigation of complex systems.
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  • 133
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    International Journal of Quantum Chemistry 6 (1972), S. 609-611 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The equivalence of the perturbation formalism, in the Rayleigh-Schrödinger frame-work, between secular and generalized secular equations is analysed.
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  • 134
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    International Journal of Quantum Chemistry 6 (1972), S. 625-637 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electronic structure and preferred conformations of F3P·BH3 and F2HP·BH3 are investigated in the framework of the CNDO/2 approximation. In complete agreement with microwave data, the staggered conformations are predicted to be the most stable ones. The barriers to internal rotation are in good agreement with experimental values (F3P·BH3: calc. = 3.03 kcal/mole, exp. = 3.24 ± 0.15 kcal/mole; F2HP·BH3: calc. = 3.63 kcal/mole, exp. = 4.05 ± 0.45 kcal/mole) and a bicentric energy partitioning shows that the variations of the total energy are completely reflected by the only variation of the interaction energy between phosphorus and H atoms bonded to boron. The analysis of the electron densities reveals the importance of the 3s(P) → 2px(B) transfer in the formation of the co-ordination. Finally, the computed dipole moment value and direction agree with corresponding experimental data.
    Additional Material: 4 Ill.
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  • 135
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    International Journal of Quantum Chemistry 6 (1972), S. 663-668 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diamagnetic susceptibility χ and magnetic shielding σ for H2+ are investigated in the range of internuclear separations R = 1.6 a.u. to R = 2.4 a.u. according to a previously reported technique. From this data values of 〈χ〉 and 〈σ〉, for which nuclear motion due to zero-point vibration and centrifugal stretching is taken into account, are calculated at 300°K. These averages are 〈χ〉 = -0.3902 α2ao3 and 〈σ〉 = 1.096 × 10-5 c.g.s. units which are approximately 3.1% and 1.4% respectively, smaller than the equilibrium values.
    Additional Material: 3 Tab.
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  • 136
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    International Journal of Quantum Chemistry 6 (1972), S. 725-746 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tables of symmetrized powers of the irreducible representations of point groups are presented together with a derivation of the formula used to obtain them. It is shown how these tables may be applied to various quantum-chemical problems.
    Additional Material: 9 Tab.
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  • 137
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    International Journal of Quantum Chemistry 6 (1972), S. 779-785 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By a proper approximation of the interaction term in a many-electron Hamiltonian the Hartree-Fock equations are decoupled. Making use of this simplification one obtains a good initial guess for the wave function with minimal computational work. Refining the procedure, the exact HF limit can be achieved. Total energies, ionization potentials and excitation energies for light atoms are calculated.
    Additional Material: 3 Tab.
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  • 138
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 139
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    International Journal of Quantum Chemistry 6 (1972), S. 57-81 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular-electronic structure of the metal phthalocyanines (Fe, Co, Ni and Cu) has been determined by the molecular orbital treatment. Coulomb integrals of the metal atom occurring in the secular determinants have been approximated equivalent to the valence state ionization energy (VSIE) of a metal orbital for a particular charge configuration. The calculated π-electron charge densities have been found to be higher on the nitrogen atoms as compared to the other atoms in the molecule. This is in agreement with the e.s.r. studies of the metal phthalocyanines. To test the correctness of the molecular orbital calculations, the π-π* transitions (14,000 cm-1 - 30000 cm-1), d-d* transitions (20000 cm-1 - 60000 cm-1) and charge transfer transitions (15000 cm -1 - 30000 cm-1) have been calculated in the metal phthalocyanine molecules. The calculated frequencies have been compared with the observed ones and found in fair agreement.
    Additional Material: 4 Ill.
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  • 140
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    International Journal of Quantum Chemistry 6 (1972), S. 101-123 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An exact cluster expansion of many electron wave functions is derived, beginning with a finite linear combination of Slater determinants rather than the more usual single determinant. This general cluster expansion is found to apply both in the case where all possible Slater determinants from a finite set of spin orbitals are included in the linear combination, and in the case where the number of determinants is restricted.The special properties of that finite linear combination of determinants closest to the exact wave function in the least squares sense are studied. These properties lead to the derivation of a general correlated wave functions method, illustrating again the close relationship between methods of this type and cluster expansion theory. Additional approximations, necessary for practical calculations, are set out.
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  • 141
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    International Journal of Quantum Chemistry 6 (1972), S. 155-166 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A first order perturbation treatment starting with SCF-MO'S in canonical or equivalent quasi-localized form is presented for the hyperfine coupling constants of vinyl and methyl radicals. The spin-polarisation contribution to hyperfine splittings is found to be large, negative for the proton of the radical center in both radicals and positive for the β protons of vinyl.
    Additional Material: 5 Tab.
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  • 142
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    International Journal of Quantum Chemistry 6 (1972), S. 593-596 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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  • 143
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 144
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general formalism is set up to apply the variation-perturbation method to the quantum theory of non-linear optical effects, in particular to the electric and magnetic birefringence (Kerr and Cotton-Mouton effects).The quantities describing these effects are obtained from the wave function Ψ0(0) of the ground state of the unperturbed molecule and the different vectors and tensors which are determined by a variation method.With this method an approximate computation of the Kerr and Cotton-Mouton constants of some simple molecules has been made.
    Additional Material: 5 Tab.
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  • 145
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    International Journal of Quantum Chemistry 6 (1972), S. 93-100 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that under certain restrictions the system of determinants ϕi(x1)ϕk(x2) - ϕk(x1)ψi(x2) constructed from two different sets of orbitals ψk and ϕk will be the complete set of functions for antisymmetrical two-electron wave functions if the condition i 〈 k is imposed.
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  • 146
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    International Journal of Quantum Chemistry 6 (1972), S. 143-153 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Green's functions for the simplest quantum mechanical systems the linear harmonic oscillator, the three-dimensional isotropic oscillator, the Morse oscillator, the Kratcer potential, and the double-minimum potential V(x) = (mw2/2)(/x/-R)2 are presented in closed analytical forms.
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  • 147
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    International Journal of Quantum Chemistry 6 (1972), S. 193-196 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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  • 148
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    International Journal of Quantum Chemistry 6 (1972), S. 201-209 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A one center method, based on the work of Karplus and Kolker, is discussed and used to calculate the induction energy, through O(R-8), for the H(ls) - H+ interaction employing two types of Gaussian basis sets constructed from functions of the form {rje-αr2}. The effective hydrogen atom excitation energies and transition multipole moment matrix elements generated in these calculations are used to calculate the dispersion energy for the H(ls) - H(ls) interaction, through O(R-10), and the R-9 triple dipole energy corresponding to the interaction of three H(ls) atoms. The results indicate that Gaussian functions can form good basis sets for obtaining long range forces for a variety of multipole interaction energies.
    Additional Material: 5 Tab.
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  • 149
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    International Journal of Quantum Chemistry 6 (1972), S. 263-269 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The paramagnetic properties of one-dimensional macromolecules with conjugated C=C bonds are discussed on the basis of low-lying quasi-homeopolar triplet excitations. A good agreement with the experimental results is shown.
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  • 150
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    International Journal of Quantum Chemistry 6 (1972), S. 289-296 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The matrices of the irreducible representations of the 3-dimensional rotation group are shown to be related to Krawtchouk's orthogonal polynomials of a discrete variable x = j - m', whose degrees are given by n = j + m. The relation follows directly from the recurrence formulas satisfied by the matrix elements and permits a concise development of the formal properties of the rotation matrices. In particular, an asymptotic relation for large j is developed that generalizes a formula first discussed for a special case by Wigner.
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  • 151
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 6 (1972), S. 23-45 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to treat the interaction energy of two molecules a standard Rayleigh-Schrödinger perturbation theory is developed. The Hartree-Fock functions of the separated molecules are used as one particle basis functions, the initial set of states being truncated and non-orthogonal. The non-orthogonality is included into the Hamiltonian by orthogonalization of the basis set. The unperturbed Hamiltonian is chosen so that it possesses the correct symmetry properties with respect to the electron permutations between different molecules. The procedure of this kind automatically results in the appearance of charge transfer states.A graphical technique is elaborated which is a modified version of the Feynman-Goldstone technique and provides a convenient representation of the interaction energy contributions of any order. As an example the first- and the second-order diagrams are considered.A correct expression for the dispersion energy is obtained which differs by a factor from that of the theory using a nonsymmetrical zero approximation.
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  • 153
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Group-theoretical methods for determining permitted terms of electrons in polyatomic molecules and complexes in the MO and HL methods are proposed. Essentially, the permutational symmetry of the electron system is utilized. Some concrete examples of the operation of these methods are considered.
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  • 154
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    International Journal of Quantum Chemistry 6 (1972), S. 131-142 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two different perturbation series (the polarization expansion and a united-atom expansion) of the ground state energy of the delta-function model for one-electron diatoms are studied and the radii of convergence are determined. For both expansions the singularity in the energy which limits the radius of convergence is a branch point with exponent one-half. The physical significance of the branch point is that for particular values of the perturbation parameter, two different energy eigenvalues coalesce. The positions of the branch points are computed as a function of the internuclear separation R. For all values of R, both series converge for all physical values of the perturbation parameters. A lower bound to the radius of convergence of the polarization expansion has been computed previously by Claverie. It is proved in the present paper that the lower bound calculation is in fact an exact determination of the radius of convergence. The results of the model study are applied to real one-electron diatoms to suggest the possible location of a branch point singularity in the energy of the ground state.
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  • 155
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    International Journal of Quantum Chemistry 6 (1972), S. 197-198 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 156
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    International Journal of Quantum Chemistry 6 (1972), S. 271-279 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Previous mathematical proofs of the non-crossing rule concerning the potential energy curves of a diatomic molecule are examined and criticised. A new treatment is presented which is simple and mathematically rigorous.
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  • 157
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    International Journal of Quantum Chemistry 6 (1972), S. 313-325 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The phenomenon of nuclear quadrupole resonance is presented from the grouptheoretical point of view. This approach allows one to discuss the splitting of the nuclear spin states without prior wave-mechanical calculation. Nuclear quadrupole moments are also compared with moecular quadrupole moments and the differences discussed. Finally the selection rules are deduced.
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  • 158
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    International Journal of Quantum Chemistry 6 (1972), S. 353-366 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new expression is given for the electron repulsion integral over Slater-type orbitals on four different centers. It is based on the asymptotic expansion derived from the bipolar expansion of a previous paper. The expression has the form \documentclass{article}\pagestyle{empty}\begin{document}$$ I\,\mathop \sim \,\sum \limits_{q_1 }^\infty \mathop \sum \limits_{q_2 }^\infty \,F_{q_1 q_2 } (R_{{\rm PQ}})\sigma _{q_1 } (A,\,B)\sigma _{q_2 } (C,\,D) $$\end{document} where qp = {np, lp, mp}. Both F and σ are closed expressions. The quantity F is a combination of incomplete gamma functions, Laguerre polynomials and spherical harmonics. It depends upon the relative coordinates of a point P on the AB axis and a point Q on the CD axis. The functions σnlm(A, B) depend on the charge distribution (χAχB); they have the character of overlap integrals and are of the form \documentclass{article}\pagestyle{empty}\begin{document}$$ \sigma _{nlm} (A,\,B)\, = \,\mathop \Sigma \limits_v \,\mathop \Sigma \limits_w \,F_{vw} (\zeta _A R_{AB},\,\zeta _B R_{AB})K_{vw} (R_{AB}) $$\end{document}
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  • 159
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    International Journal of Quantum Chemistry 6 (1972), S. 387-399 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: SCF-LCAO-MO-CI semi-empirical π-electron calculations have been made of the first two singlet transitions and ionization potentials of hydroxy-, methyl- and hydroxy-methyl substituted p-benzoquinone, using a modified Pariser-Parr-Pople method. The various molecules could be divided into two classes on the basis of their first π-electron transition, namely, those in which the 3-position was occupied and others where this position was vacant.
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  • 160
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    International Journal of Quantum Chemistry 6 (1972), S. 519-523 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Attention is called to the attractive cusp conditions as useful constraints in fixing the elements of the electron density matrix. An equation for determination of pure state densities satisfying arbitrary constraints is reviewed, and a detailed formalism for using cusp conditions with this equation is displayed. A calculation is done using the nitrogen molecule as an example.
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  • 161
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    International Journal of Quantum Chemistry 6 (1972), S. 211-224 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variational formulation of the Hartree-Fock-Roothaan (HFR) theory for open shell ions in presence of time dependent perturbations is presented. The theory has been used to calculate the dynamic polarizabilities of the first three ions of the Li sequence. The polarizability values, extrapolated to zero frequency, show good shell by shell agreement with the corresponding static results. The polarizability graphs display resonance behaviour at the transition frequencies of the ions, and a study of these points leads to analytic HF wave functions for their low lying excited states. The calculated transition frequencies are in excellent accord with the experimental values. The calculated oscillator strengths for the 2s → np transitions are in reasonable agreement with the extensive multiconfiguration calculations of Weiss and the available experimental results.
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  • 162
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    International Journal of Quantum Chemistry 6 (1972), S. 225-261 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hougen has established, for quasi-rigid molecules, the relationship between permutationinversions acting on the molecular Hamiltonians written in Cartesian co-ordinates and permutation-rotations (perrotations) of symmetry acting on nuclear equilibrium configurations. We extend these relations to the case of non-rigid molecules. For this, we introduce kinetic perrotations which act on nuclear equilibrium configurations in the same way as do Altmann's isodynamic operators. We show that isodynamic operators do not always form a group. Moreover, their action cannot be extended to the electrons. They cannot be used for the classification of molecular wave functions. This classification is achieved by using the group of Longuet-Higgins and the group of the corresponding feasible perrotations.
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  • 163
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A separated pair calculation of the electronic structure of the Li2O molecule is described. Rather extensive calculations were made of the potential surface for symmetric configurations of Li2O using a double zeta Slater orbital basis. A linear configuration with LiO bond length of 1.71 Å is found to be most stable. The electron distribution and correlation effects are discussed.
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  • 164
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    International Journal of Quantum Chemistry 6 (1972), S. 347-352 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An expansion is given for the inverse interelectronic distance in terms of the coordinates of the two electrons. The terms in the expansion contain the coordinates of the first electron with respect to two centers A, B and those of the second electron with respect to two centers C, D.
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  • 165
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    International Journal of Quantum Chemistry 6 (1972) 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 166
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    International Journal of Quantum Chemistry 6 (1972), S. 413-438 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The one-electron integral over Slater-type atomic orbitals centered at A and B and irregular solid spherical harmonics as operator centered at C is evaluated analytically by using elliptical coordinates and translation of the solid spherical harmonics from center C to either focus A or B. A special case is the three-center nuclear attraction integral which is also evaluated by means of the Neumann expansion and expressed without associate Legendre functions of the second kind. The strict observation of the charge distribution concept leads to compact expressions for the integral. It has the further advantage that the charge density distributions which have been developed for the two-center cases and used in calculations for diatomic molecules can be utilized.
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  • 167
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    International Journal of Quantum Chemistry 6 (1972), S. 47-55 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: π-electron SCF-MO theory in its variable electronegativity formalism has been applied to some monosubstituted benzenes. Calculated charge densities and bond orders for the ground and the first excited electronic states are correlated with chemical reactivity and the changes in molecular geometry on electronic excitation. The calculated results for spectra are compared with those obtained using the PPP method and also with the available experimental data.
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  • 168
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    International Journal of Quantum Chemistry 6 (1972), S. 596-597 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 169
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    International Journal of Quantum Chemistry 6 (1972), S. 599-599 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 170
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Wave functions for impurities or local complexes in crystals are usually described within one of the two popular schemes furnished by the MO and the HL methods. The purpose of the present note is to draw attention to a set of tables which allow a translation between these two descriptions.
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  • 171
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    International Journal of Quantum Chemistry 6 (1972), S. 647-650 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The corresponding orbital energy expression of Lefebvre and Prat [1] has been developed and used to obtain some extended Hartree-Fock results for Lithium Hydride.
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  • 172
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    International Journal of Quantum Chemistry 6 (1972), S. 669-680 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A computational method for calculating quadrupole moments from molecular wave functions in a Slater orbital basis set is described. Using both IEHT and CNDO wave functions quadrupole moments for a series of polyatomic molecules are calculated. They are compared with experimental results and the IEHT wave functions are found to give agreement with experiment while CNDO wave functions do not. The importance of bicentric densities (overlap densities) in the calculation of multipole moments is shown. This is followed by a discussion of the usefulness of these wave functions for a quantitative characterization of the electronic structure of large molecules.
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  • 173
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    International Journal of Quantum Chemistry 6 (1972), S. 761-777 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of the representation theory of symmetric groups to the solution of quantum chemical problems is discussed. This is done using matrices which do not represent Sn in the normal sense, but which are much simpler to calculate than the Yamanouchi-Kotani representation. A complete discussion of the calculation of these matrices is given.
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  • 174
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    International Journal of Quantum Chemistry 6 (1972), S. 793-795 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 175
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    International Journal of Quantum Chemistry 6 (1972), S. 799-799 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 176
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    International Journal of Quantum Chemistry 6 (1972), S. 849-858 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quasi-relativistic approach to the MO-LCAO method is formulated taking into account the relativistic effects with an accuracy up to (v/c)2 terms, the relativistic part of the electronic interaction in the Hamiltonian being neglected. In the framework of this approximation a set of SCF equations of the Roothaan form is derived; here only the relativistic analogue to the closed shell systems with one-determinant wave functions is considered. In so doing three types of relativistic corrections arise which are quite similar to those of the Pauli equation for one-electron atoms. The new matrix elements appearing due to these corrections can be reduced to some common integrals, which have to be calculated with relativistic radial atomic functions. The method allows a semi-empirical approach to the problem and does not require the Dirac four-component atomic functions (unknown in the most cases), thus making possible approximate quasi-relativistic electronic structure calculations of heavy-atom compounds.
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  • 177
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    International Journal of Quantum Chemistry 6 (1972), S. 911-917 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Schrödinger equation for the hydrogen molecular ion is written as a perturbed united atom which is then treated as a generalized eigenvalue equation. The ground state energy is calculated through third order for small internuclear distances.
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    International Journal of Quantum Chemistry 6 (1972), S. 949-966 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Closed form one centre partial wave perturbation results are obtained through second order in the energy for H2+-like molecules with arbitrary nuclear charges. The expansion centre for the method is taken at an arbitrary point along the internuclear axis and the zeroth-order wave function is a screened “1s” function centred at the expansion point. Various fixed one centre calculations of other workers for the lsσ states of H2+ and HeH++ and for the 2pσ state of HeH++ are generated as limiting cases of this more general treatment. The floating one centre perturbation results for the 1sσ states of H2+ and HeH++ are used as models for discussing the usefulness of allowing the expansion centre in the one centre method to be a function of nuclear configuration.
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  • 179
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    International Journal of Quantum Chemistry 6 (1972), S. 617-623 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An economic algorithm for storing and processing two-electron integrals arising in LCAO-MO calculations is presented. The integrals are sorted prior to the SCF iterative scheme, classified according to equivalences in the orbital indices and finally stored on separate files that contain only integrals of one type. The novel approach of physically separating the integrals according to category is shown to be more efficient than random storage. Actual computing times for the new technique are tabulated for a representative number of molecular systems and compared with times obtained using previously reported methods.
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  • 180
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    International Journal of Quantum Chemistry 6 (1972), S. 651-661 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variation-perturbation method, analogous to a technique devised by Das and Bersohn for the study of the hydrogen molecule, is developed for calculation of the diamagnetic susceptibility χ and magnetic shielding σ and is applied to a study of the hydrogen molecule ion. Two approximations are investigated-in a first approximation, χ = -0.37814α2ao3 and σ = 1.112 × 10-5 c.g.s. units and in a second approximation, χ = -0.37569α2ao3 and σ = 1.128 × 10-5 c.g.s. units.
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    International Journal of Quantum Chemistry 6 (1972), S. 681-700 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Canonical transformations have been widely used to simplify Hamiltonians and other operators. In molecular and in solid state theory, the so-called Van Vieck expansion is usually employed for this purpose while in theories of particles interacting with fields a combination of canonical transformations in closed form with Van Vleck type expansions has been found effective. For some of the transformations used in applications formulas in closed form are well known. It will be shown here that such formulas can be derived whenever the transformation function is bilinear in the canonical variables, and further that the use of matrix operators makes it possible to simplify these derivations substantially. The Cayley-Hamilton theorem is then used to express the expansions for the matrix operators in closed form. The number of separate operator terms appearing in the formulas thus obtained is the same as the rank of the matrices used. To calculate the coefficients of these operator terms a new type of special functions is introduced. The resulting linear canonical transformations include generalized rotations in both ordinary and phase-space. Explicit results have been obtained for several two- to four-dimensional problems.
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  • 182
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: First-order wave functions and binding energies of the 1sσg and 2pσu states of H2+ are calculated by simple methods for internuclear separations between 0.2 and 10a0. An exact perturbation treatment of the lsσg state with a zeroth-order function of the form N exp (-sRλ/2) exp (sR μ2) yields only fair results. An alternative method starts with zeroth-order functions of the form N exp (-sRλ/2)[exp (-sRμ/2) ± exp (sRμ/2)] for the 1sσg and 2pσu states, respectively. An approximate first-order trial function is set up and the energies are determined variationally. For both states the results are comparable to those obtained by exact perturbation treatments of the same order.
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    International Journal of Quantum Chemistry 6 (1972), S. 795-797 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    International Journal of Quantum Chemistry 6 (1972), S. 843-847 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The procedure proposed by Silverstone and others to modify virtual levels in SCF theory is extended as a technique to be used in any type of generalized secular equations. Some useful results are obtained.
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  • 185
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron density and spatial correlation as given by the MO, VB and AMO methods for H2 and H6 are studied by means of diagrams. For comparison, diagrams representing accurate wave functions for H2 are also given. The study of model functions representing localized bonds leads to results concerning the nature of localized electron pairs in agreement with those of Lennard-Jones.
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    International Journal of Quantum Chemistry 6 (1972), S. 439-448 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trial wave functions, written as the sum of a configuration interaction expansion and an explicitly correlated term which is not antisymmetric, are proposed for use in calculating the electronic properties of atoms and molecules. A variational principle, modified to allow the use for such partially antisymmetric wave functions, is developed. It is shown that the consequences of partial antisymmetry on calculated expectation values can be estimated. The method avoids difficult three-electron integrals which arise in other theories.
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    International Journal of Quantum Chemistry 6 (1972), S. 473-489 
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    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The analysis of the equations of the unrestricted Hartree-Fock (UHF) method for polyenes CNHN+2 with even and odd N » 1 is carried out. The equations of the UHF method are shown to be the same in both cases. The comparison of the UHF method with the extended Hartree-Fock (EHF) method applied to large systems is performed. The ground state and π-electron spectra of long cumulene chains CNH4 are treated by the EHF Method. The end effects are taken into consideration. It is shown that the EHF method gives a finite value of the first optical transition frequency and, at the same time, zero value of torsion barrier of end CH2-groups in long cumulene chains (N → ) in contrast to previous calculations of cumulenes by the Huckel method and the restricted Hartree-Fock method.
    Additional Material: 1 Ill.
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  • 188
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    International Journal of Quantum Chemistry 6 (1972), S. 525-539 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The valency state (vs) concept is analyzed in the Hartree-Fock approximation. A valency state “standard” is defined for atoms at infinite separation. A molecular orbital valency state (Movs) is defined from a partitioning technique (bond energy analysis) previously introduced for the Hartree-Fock molecular wave functions. The Movs for a given atom in a molecule is much higher in energy than the vs and its energy varies from molecule to molecule depending on the exact field of the surrounding atoms. The examples selected in the discussion are the CH4 CH3F, CH2F2, CHF3 and CF4 molecules.An analysis of the orbital energies is then given in terms of the bond energy. The importance of the rearrangement effects following ionization of inner shell electrons (simulation of ESCA type experiments) is illustrated with computations of the positive ion for methane and its fluoroderivatives. It is concluded that rearrangement following ionization from inner shells is as important as rearrangements following ionization from valency electrons. A direct consequence is that the orbital energies should not be equated to the inner shell ionization potentials. The computation of such ionization potentials agrees to about 99.5% with ESCA data, when the energy of both the neutral and ionic species are computed; the use of the orbital energies limits this agreement to about 95%.
    Additional Material: 4 Ill.
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  • 189
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Modern techniques for multidimensional numerical integration, Korobov's and Sobol's formulas namely, are used for the direct computation of matrix elements between the localized molecular orbitals needed for a configuration interaction calculation by a perturbation method. A minimal orbital basis of Slater functions is used for formaldehyde and ethylene taken as example. The resulting precision is satisfactory.
    Additional Material: 5 Tab.
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  • 190
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method is presented which leads to accurate Fourier transform values of any 1s-1s Slater-type orbital overlap distribution. The numerical merits are discussed and illustrated by some examples.
    Additional Material: 1 Tab.
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  • 191
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    International Journal of Quantum Chemistry 6 (1972), S. 639-646 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study is made of a variational principle which provides upper and lower bounds for the polarizability under a perturbation with imaginary frequency. As an example bounds for the imaginary frequency polarizability of atomic hydrogen and ensuing limits for the constant of van-der-Waals interaction of two hydrogen atoms are calculated.
    Additional Material: 3 Tab.
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  • 192
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    International Journal of Quantum Chemistry 6 (1972), S. 701-716 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of the Renner effect in X2Y2 and X2YZ linear molecules is considered. The Renner equations are obtained with the help of the Born-Oppenheimer method. It is shown that these equations contain two Renner parameters for an X2Y2 molecule and three Renner parameters for an X2YZ molecules. Assuming these parameters to be small enough, an approximate solution of the Renner equations is obtained with the help of perturbation theory. Some general qualitative results are obtained in the first order of the perturbation theory; the second order calculations are made for some specific cases. The theoretical results are used to consider experimental data concerning the vibrational structure of the 1IIu - 1Σg+ electronic transition in C2H2 and C2D2 molecules. The frequencies of the bending vibrations and the Renner parameters are calculated for the electronic 1IIu-state mentioned.
    Additional Material: 2 Ill.
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  • 193
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    International Journal of Quantum Chemistry 6 (1972), S. 747-759 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Molecular orbitals of zinc phthalocyanine have been calculated with the help of a kind of extended Hückel technique. Coulomb and exchange integrals of the zinc atom have been approximated in a way equivalent to the valence state ionization energies of the particular metal orbital for a particular charge configuration. π-electron charge densities over the atomic sites have been calculated and found in agreement with the observed results. π-π* absorption (11000 cm-1 - 32000 cm-1) and charge transfer absorption (19000 cm-1 - 40000 cm-1) frequencies have also been calculated and found in agreement with the experiment.
    Additional Material: 8 Tab.
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  • 194
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    International Journal of Quantum Chemistry 6 (1972), S. 787-791 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The solution of the time dependent Schrödinger equation, including renormalization of the wave function, is used to obtain quantum mechanical expressions for the optical rotation and the circular dichroism. The use and form of the radiative damping term is examined with respect to its effects in the circular dichroism formula.
    Type of Medium: Electronic Resource
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  • 195
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    International Journal of Quantum Chemistry 6 (1972), S. 801-817 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: General expressions are obtained for the energies of complex and real forms of any hydrogenic orbital (n, l, m) in a cluster of point charges of any geometry. This is a perturbation calculation of hydrogenic Rydberg orbitals in a one-electron hard core approximation. A model calculation of 3d-electrons of carbene, ethylene and benzene with varying charge distribution is given.
    Additional Material: 6 Ill.
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  • 196
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    International Journal of Quantum Chemistry 6 (1972), S. 859-880 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An outline is given of a semi-empirical scheme for molecular-orbital calculations on transition-metal complexes according to a revised INDO procedure. To judge the reliability of the results of the calculations, the charge-transfer transitions of a number of complexes have been calculated and compared with experimental data. Both for the excitation energies and for the oscillator strengths the agreement is very satisfactory. With respect to the sequence of occupied metal and ligand orbitals it was found that for closed-shell d6 and d8 systems the molecular orbitals which are mainly composed of metal d orbitals have a lower energy than the orbitals built up from ligand p orbitals. Calculations by the extended Hückel method and other similar schemes give the d orbitals as the highest occupied ones as a result of a bad approximation of the diagonal elements of the Fock matrix. The consequences for the interpretation of photo-electron spectra of transition-metal complexes are discussed.
    Additional Material: 3 Ill.
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  • 197
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    International Journal of Quantum Chemistry 6 (1972), S. 919-924 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: After a brief discussion of progress in the theory of icosahedral molecules, the terms arising from simple electronic configurations are deduced from tables of symmetrized powers of representations previously published by the author.
    Additional Material: 4 Tab.
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  • 198
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    International Journal of Quantum Chemistry 6 (1972), S. 967-973 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Localized valence molecular orbitals have been obtained for SO42-, SO2F2, ClO3F and SOCl2 by the method due to Boys and Foster. The bonding in these molecules, in which the second row atom is exhibiting an excess valency, is discussed in terms of the form of these localized orbitals. The bonding of the second row atom to an oxygen atom is described by three bent bond orbitals, whilst bonding to a halogen atom is described by a single bond orbital. The participation of 3d functions in the various bonding and nonbonding orbitals is analysed in this localized orbital framework.
    Additional Material: 3 Tab.
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  • 199
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    International Journal of Quantum Chemistry 6 (1972), S. 989-999 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methods of intermediate Hamiltonians and of inner projections for the determination of lower bounds of eigenvalues of a Hermitian operator H are analysed and reformulated as linear matrix problems. Submatrices T which are only defined implicitly through the product TTd̊ are best represented in triangular form. If the subspace complementary to the subspace determining the inner projection can be subdivided with different lower bounds for H, the bounds for the eigenvalues can be further improved. The new formalism is applied to obtain crude lower bounds for the ground state of the helium atom, using only 2 × 2 and 3 × 3 matrices.
    Additional Material: 2 Tab.
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  • 200
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    International Journal of Quantum Chemistry 6 (1972), S. 465-472 
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general theory of the extended method of calculation of atomic structures having complex configurations is presented. It is based on the correspondence between the radial integrals of the ordinary method and the linear combinations of those of the extended method. The rules for going over from the ordinary method to the extended one are given.
    Type of Medium: Electronic Resource
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