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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 110 (1999), S. 4213-4220 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The minimal deformation criterion, previously proposed for the partition of the molecular density into atomic contributions, is updated and extended. For any Gaussian basis set, these atomic contributions are expanded in a series of real spherical harmonics by radial factors. The terms with l=0 determine the spherical parts of the atomic clouds and the remaining ones, their deformations. This detailed description is complemented with a simplified representation of the molecular density in terms of atomic charges and multipoles. Moreover, these descriptions give a simple way to calculate the electrostatic potential of the molecule as well as the electrostatic interaction between molecules. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 9807-9816 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The numerical and analytical procedures, used for calculating exchange integrals with Slater functions, fail to give high accuracy for large quantum numbers and some values of the parameters. We propose here an algorithmic approach based on recurrence relations which start from some simple functions. An extensive study in which exponents, interatomic distances, and quantum numbers were varied proves that the new procedure is fully reliable. Finally, the cost of the procedure is analyzed, including the effect of the number of terms needed to attain a given accuracy. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 1788-1799 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In a recently reported method, the molecular density is partitioned in minimally deformed atomic contributions, which are expanded in spherical harmonics times radial factors. Here we use this representation to express the electrostatic potential of the molecule, the force on its nuclei, and the conformational variations of energy in terms of some simple integrals of the atomic radial factors. As a first application, we analyze the relationship between the density and the binding forces (and the bonding energy) in the diatomic molecules of the first row atoms. Two types of forces act on each nucleus: the self-pulling exerted by its own cloud and the external force due to the remaining atoms. The self-pulling comes only from the dipole type term of the atomic density. The external force comes from the other clouds and nuclei and is dominated by the effective charges which depend on the outermost region of the charge term. Analyzing the progressive deformations of the atoms when they approach each other, the forces associated with these deformations and their contributions to the energy, one has a detailed description of the chemical bond which is complementary, and in many aspects more appealing, than the conventional ones. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The effects of audio sidebands from the main rf of the NSLS VUV storage ring on beam motion and specifically on spectral reproducibility in the infrared region were investigated. For this spectral region it is advantageous to use Michelson interferometers because of their high throughput (Jacquinot advantage). A second advantage is that interferometers inherently give a multiplex or Felgett advantage, since one is always looking at all the wavelengths for all of the measuring time, even though there is only one detector. In such instruments it is beneficial to scan the moving mirror at a fast rate so that any mechanical or other low-frequency noise shows up as a slow modulation in the interferogram and disappears altogether in the Fourier transform from the spectral region of interest. However, audio-frequency sidebands appear from the rf energy restoring cavity as noise on the beam. These always occur at multiples of 60 Hz and can thus be readily identified. They can also be confirmed by changing the mirror velocity which changes where they appear in the spectra in a predictable way. In the present work, spectra were measured while simultaneously reducing and shifting the sidebands in the rf and thus the effects were correlated and ultimately eliminated as a source of noise. Ultimately reproducibilities of 〈1% in 15 s of scanning time across the entire spectral region from 800 to 4000 cm−1 with a sample throughput of only 10−10 m2 sr were achieved. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 4213-4222 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new algorithm for the calculation of molecular integrals involving STOs is reported. The algorithm enables us to obtain every two-center one-electron integral and the long-range many-center one- and two-electron integrals. The efficient implementation of the algorithm is discussed and its performance is thoroughly tested. The analysis on the stability of the relations employed in the calculation of multipolar moments is included. Futhermore, the computer time required to carry out each step (construction of basic matrices, calculation of multipolar moments, and calculation of two-electron integrals) has also been analyzed. The range of validity of this approach is shown in several molecular integrals.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 4204-4212 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A method for the calculation of many-center integrals involving Slater-type orbitals (STOs) is reported. The method is based on the separation of the short- and long-range terms of the potentials generated by charge distributions. The calculation of three-center nuclear attraction integrals and many-center electron repulsion integrals, when the short-range contributions are negligible, is formulated in terms of multipolar moments of charge distributions. Recurrence relations for obtaining the multipolar moments, which enable us to reduce their calculations to the evaluation of some basic integrals, are reported.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 5032-5039 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We discuss the calculation of the general three-center nuclear attraction integrals with Slater type orbitals using a one-center expansion method which exploits the algorithms previously developed by us for long-range integrals. From the analysis of the numerical stability, accuracy, and computational cost we conclude that the reported procedure is suitable for the calculation of these integrals with any desired precision. Moreover, we have found that most of these integrals can be obtained with high accuracy at a very low computational cost, but the procedure could be too expensive for a few of them.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 97 (1992), S. 7613-7622 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We develop and check an updated version of the ellipsoidal coordinate methods for the calculation of three-center nuclear attraction integrals with Slater-type orbitals (STOs). A first set of recurrence relations allows us to express these integrals in terms of some basic potentials. The basic potentials are classified in short- and long-range types, and then calculated in specific ways from auxiliary functions obtained by using a new set of both stable and fast recurrence relations. Numerical tests show that the procedure enables to reach very high accuracy in the integrals with a low computational cost.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 19 (1972), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— Amino acid incorporation in vivo was investigated in the cortex and hippocampus of rats raised in enriched and deprived environments for various periods of time following weaning. At early times after weaning (7 days), the incorporation of l-[3H]leucine into all sub-cellular fractions of both cortex and hippocampus was higher in enriched than in deprived rats. At 16 days, incorporation into synaptosomal sub-cellular fractions was higher in enriched than in deprived hippocampus, and lower in enriched than in deprived cortex; incorporation into perikaryal fractions of both brain regions was the same in the two groups of animals. Incorporation into subcortical nuclear protein fractions was higher in enriched rats at this time. At 35 days, the only difference between enriched and deprived rats was a lower incorporation into cortical synaptosomal sub-fractions in the former. Experiments involving double labelling and electrophoresis indicate that there is no stimulation or inhibition of the synthesis of any particular protein in hippocampal nuclear and synaptosomal sub-fractions of enriched rats. Synaptosomal proteins of cortex have a greater half-life in enriched than in deprived rats; proteins of perikaryal fractions of cortex, and of all fractions of hippocampus, are turning over at the same rate in enriched and deprived animals.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    FEBS Letters 286 (1991), S. 25-27 
    ISSN: 0014-5793
    Keywords: Asymmetric acetylcholinesterase ; Basal lamina proteoglycan ; Chondroitinase ; Collagen-like tail ; Heparinase ; Skeletal muscle
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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