Library

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Calcul du champ de force de valence et des coordonnees normales de l'ether dimethylique a partir des frequeneces de vibration des molecules (CH3)2O, (CD3)2O et CH3OCD3
    Amsterdam : Elsevier
    Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy Section 24 (1968), S. 2165-2173 
    Details
    ISSN: 0584-8539
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0584-8539(68)80278-8
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Perturbation theory using series expansions and the Riccati equation (1995)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 103 (1995), S. 3006-3013 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An algebraic procedure is proposed for the analytical solution of Schrödinger equations that can be viewed as a factorizable equation with an adequately chosen perturbation. This procedure relies on the solution of the Riccati equation associated with the given eigenequation and the use of power series of suitable functions which are specific to each factorization type. As illustrative examples, analytical solution of the symmetric anharmonic oscillator, perturbed Morse oscillator and singular anharmonic oscillator equations are carried out. Further applications are pointed out. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.470489
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Open perturbation and the Riccati equation: Algebraic determination of the quartic anharmonic oscillator energies and eigenfunctions (1997)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 38 (1997), S. 5483-5492 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: An algebraic procedure is proposed for the analytical solution of Schrödinger equations that can be viewed as a factorizable equation with an additional potential V(x). Once V(x) has been expanded in a series of suitable x-basis functions u=u(x), which are specific to each factorization type, the solution of the Riccati equation associated with the given equation is performed by means of an open perturbation technique, i.e., at each order of the perturbation, an additional balance u-dependent term is introduced so that the resulting equation becomes solvable. Since the unperturbed potential involves the whole given potential and since the balance term is expected to be small, improved results are expected at low orders of the perturbation, even at the zeroth order. The procedure, well adapted to the use of computer algebra, is applied to the solution of the gx4-anharmonic oscillator equation: by means of very simple algebraic manipulations, the trend of the exact values of the energies is rather well reproduced for a large range of values of the coupling constant (g=0.002 to g=20000). © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.532147
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Perturbed factorization of the singular anharmonic-oscillator eigenequation (1994)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 35 (1994), S. 6244-6269 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The perturbed-ladder-operator method is applied to the solution of the perturbed eigenequation {(d2/dx2)−[m(m+1)/x2]−b2x2+V(x)+Λ}Ψ θix)=0 where V(x)=b1(1/x)2+b2(1/x)4+... is a singular perturbation. This method, which is the extension of the Schrödinger–Infeld–Hull factorization method within the perturbation scheme, provides closed form expressions of the perturbed eigenvalues and ladder functions, by means of algebraic manipulations. As an illustrative application, an analytical solution of the spiked-harmonic-oscillator eigenequation {(d2/dx2)−b2x2−(λ/x4)+E}Ψ(x)=0 is worked out up to the second order of the perturbation, by considering specifically adapted m- and λ-dependent perturbing and unperturbed potentials in order to tentatively avoid the known difficulties of convergence of the perturbation series. Closed form expressions of the λ/x4-anharmonic-oscillator energies are obtained in terms of the coupling constant λ and the quantum number v: results following from these expressions are compared with exact available values. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.530673
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Intermolecular interactions-dependence on inter- and intra-molecular distances. A configuration interaction study of the H2...H2 system (1972)
    Springer
    Theoretical chemistry accounts 25 (1972), S. 130-137 
    Details
    ISSN: 1432-2234
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Potentialkurven für zwei H2-Moleküle werden mit Hilfe eines SCF-MO-LOGO-CI-Verfahrens berechnet. Die Abhängigkeit der Wechselwirkungsenergie von der Orientierung sowie der inneren Geometrie der beiden Moleküle wird untersucht. Die numersichen Ergebnisse zeigen: a) die abstoßende Wechselwirkungsenergie steigt mit wachsenden intramolekularen Dimensionen, und b) dieser Energieanteil zeigt ungefähr Additivität entsprechend der Zahl der gestreckten Wechselwirkungspartner. Die anziehenden Anteile der Wechselwirkung zeigen ähnliches Verhalten wie die abstoßenden. Eine einfache qualitative Erklärung für dieses Verhalten wird vorgeschlagen.
    Abstract: Resume Les courbes d'énergie potentielle du systeme formé de deux molécules H2 sont déterminées par la méthode SCF-MO-LCGO-CI et la dépendance de l'énergie d'interaction en fonction de l'orientation et de la géométrie est explicitée. Les résultats montrent que: a) la partie répulsive de l'énergie d'interaction croît avec les dimensions intramoléculaires du système, b) la dépendance est, grosso modo, additive en fonction du nombre de partenaires ≪étirés≫. La partie attractive de l'énergie d'interaction présente le méme comportement que dans le cas répulsif. Une tentative d'explication qualitative simplifiée de ces résultats est présentée.
    Notes: Abstract The potential energy curves for two H2 molecules are calculated by a SCF-MO-LCGO-CI procedure. The orientational and internal geometry dependence of the interaction energy is studied. Numerical results show: a) that repulsive interaction energy increases with increased intramolecular dimensions and b) that it has a rough additivity dependence with the number of stretched partners. The attractive interaction energies display a behavior similar to the repulsive one. A simple qualitative explanation for this fact is advanced. is advanced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01135639
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Méthode des Biorbitales: Application Préliminaire au Calcul de l'Energie de l'Etat Fondamental de l'Atome de Beryllium (1967)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 1 (1967), S. 327-335 
    Details
    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
    Description / Table of Contents: The ground-state electronic energy of Be is calculated using the method of biorbitals (SCF-BI). In this method the wave function is represented by an antisymmetrized product of identical pair functions. The basic set used to develop the biorbitals consists of the Watson s and p orbitals. The pair function is presumed to describe a singlet pair state. The energy associated with this function is minimized using a steepest descent procedure. A value of 0.0414 a.u. was found for the correlation energy, which is 44% of the total correlation energy. The SCF-BI method is compared with the CI method. The relationships are established between the expansion coefficients of both methods. The occupation numbers of orbitals are calculated.
    Abstract: Die elektronische Energie des Grundzustands des Be-Atoms wird mit der Methode von Biorbitalen berechnet. Die Wellenfunktion wird in dieser Methode von einem antisymmetrischen Produkt identischer Paarfunktionen repräsentiert. Die Biorbitale werden in Watson's s und p Orbitale entwickelt. Die angewendeten Paarfunktionen beschreiben Singlettzustände. Die Energie ist mit einer Methode von steilstem Abstieg minimisiert worden. Man findet 0, 0414 a.E. für die Korrelationsenergie, d.h. 44% der theoretischen Korrelationsenergie. Die SCF-BI-Methode wird mit der Konfigurationswechselwirkungsmethode verglichen. Die Beziehungen zwischen den Koeffizienten der beiden Methoden werden abgeleitet und die Besetzungszahlen gegeben.
    Notes: L'énergie électronique de l'état fondamental de l'atome Be a été calculée en utilisant la méthode des biorbitales (SCF-BI) dans laquelle la fonction d'onde est représentée par un produit antisymétrisé de fonctions de paire identiques. Les fonctions de base sur lesquelles les biorbitales sont développées sont les orbitales s et p données par Watson. Les fonctions de paire introduites correspondent à des états singulets. L'énergie a été minimisée directement par un procédé de descente selon la pente maximale. On trouve 0,0414 u.a. pour l'énergie de corrélation soit 44% de l'énergie de corrélation théorique. On compare la méthode (SCF-BI) à la méthode (IC) d'interaction de configuration. On établit des relations entre les coefficients dans les deux méthodes. On donne les nombres d'occupation des orbitales.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560010404
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Matrix elements and their selection rules from ladder operator considerations (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 11 (1977), S. 451-472 
    Details
    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: Within the Schrödinger-Infeld-Hull factorization framework it is shown that, by introducing a parameter ε in the quantization condition, that is, ε(j-|m|)=integer ≥ 0, and, thus, considering “symmetrized” ladder operators, one can use the same formulas to handle both class I (ε = +1) and class II (ε = -1) problems. Starting from this unified point of view, after building up the associated angular momentum operators and their ε-dependent eigenfunctions, one unique closed-form expression of the coupling coefficients is obtained. This expression embodies many sparse and known previous results, without being more intricate than any of them. The basic material, allowing the application of a Wignera-Eckart theorem to matrix elements of an operator on the basis of eigenfunctions of factorizable equations, and a quick determination of the associated selection rules are given. Some examples are treated as an illustration.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560110309
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Theory of biorbitals. Study of conjugated systems in their ground and excited electronic states (1969)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 3 (1969), S. 205-218 
    Details
    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 biorbital theory called also “identical geminals theory” is applied to the study of a number of conjugated molecules. All basic integrals are determined by means of the Pariser-Parr-Pople procedure. The biorbital theory reproduces about 40 per cent of the correlation energy of the ground state of the molecule; this number is raised to about 70 per cent for the lowest triplet state. The low lying excited states are well represented from the point of view of transition energy as well as from the point of view of symmetry. The occupation number matrix and the charge-bond order matrix are defined and discussed. The overall chemical description of conjugated molecules produced by the biorbital theory is similar to that produced by other theories of electronic structure of molecules. It is concluded that the biorbital theory provides a description the quality of which is, roughly speaking, about half way between those provided by the SCF-MO and complete CI theories, respectively.
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560030206
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...