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  • 1
    Electronic Resource
    Electronic Resource
    Theoretical study of the proton affinities of 2-, 3-, and 4-monosubstituted pyridines in the gas phase by means of MINDO/3, MNDO, and AM1 (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 449-467 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Proton affinities (PAs) of 2-, 3-, and 4-monosubstituted pyridines in the gas phase are calculated using the MINDO/3, MNDO, and AM1 methods. The following substituents are considered: F, Cl, CN, CH3, CF3, CHO, NO2, NH2, N(CH3)2, OCH3, and SCH3. The results are compared with experimental values. It is found that all MINDO/3 PAs are ca. 6% too high (mean value) compared to the experimental results; on the other hand, the MNDO values are ca. 7% too low (mean value). However, a much better agreement has been observed for the AM1 method where the theoretical values are only ca. 2.4% too low (mean value). Correlations between the calculated proton affinities on one hand and the charges on the acid H atom and Hammett constants on the other hand are studied. Particularly good linear relationships are found for the 4-monosubstituted compounds within the AM1 formalism.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540100403
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  • 2
    Electronic Resource
    Electronic Resource
    Cluster analysis of periodic distributions; application to conformational analysis (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 6 (1985), S. 216-228 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A method is described to analyze observed conformations for molecular fragments with more than three torsional degrees of freedom. The method is an adaption of statistical cluster analysis to multidimensional, symmetric, periodic distributions of data points. Application to the molecular fragment M(PPh3)2 with eight torsional degrees of freedom reveals a model of conformational interconversion. The model implies gearing motion of the two PC3 fragments alternating with stepwise inversions of the helicities of the PPh3-propellers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540060309
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  • 3
    Electronic Resource
    Electronic Resource
    Operational method of data treatment (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 6 (1985), S. 229-236 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A new instrument of exploration can be used to develop unrecognized connections among points in a variety of geometric designs. Operational methods are used to derive the relationships, and a new approach to extremum location is demonstrated. The technique is suitable for interpolation problems which arise in experimental design and the treatment of data.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540060310
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  • 4
    Electronic Resource
    Electronic Resource
    General expressions for monocenter repulsion integrals in a basis of real atomic orbitals (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 6 (1985), S. 343-349 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: General expressions for monocenter electron repulsion integrals in a basis of real atomic orbitals are derived in terms of the radial integrals Rabcdk. The final expressions for these integrals can be classified into five main classes which are characterized by the angular part of the real atomic orbitals. For a basis of real s, p, d, and f AO's the total number of monocenter repulsion integrals is 65536, from which 6652 are different from zero. The nonzero integrals can be classified into 430 groups which contain integrals of equal value.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540060503
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  • 5
    Electronic Resource
    Electronic Resource
    A note on torsional force constants in molecular mechanics for a methyl group attached to a conjugated system (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 6 (1985), S. 478-480 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The molecular mechanics (MMP2) description of the torsion of a methyl group attached to a conjugated system has been improved by using bond order dependent torsional force constants.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540060517
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  • 6
    Electronic Resource
    Electronic Resource
    A parallel molecular dynamics strategy (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 6 (1985), S. 634-646 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: This article presents a strategy to perform molecular dynamics simulations using parallel processing techniques on a parallel-distributed loosely coupled system consisting of IBM host computers (4341 and 4381) with attached scientific processors (FPS-164). This substantially enhances our ability to perform fast and more realistic large scale many-body trajectory simulations. A powerful extention of the computational range of molecular dynamics the parallel approach offers the opportunity to substantially reduce the simulation time to allow a longer simulation period to study more realistic models and larger systems. It is flexible and uses, for the most part, standard products and straightforward implementation with a broad range of applicability. The implementation of a simulation of water molecules with the inclusion of two- and three-body interactions is discussed. Some considerations in the design and implementation of parallel programs on a loosely coupled system are also presented.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540060617
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  • 7
    Electronic Resource
    Electronic Resource
    On the Use of Constraints in Molecular Mechanics. Rigid Group Refinement (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 7 (1986), S. 476-481 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: It is shown how the refinement of groups of atoms as rigid entities can be implemented in a molecular mechanics program. The method is worked out for the Newton-Raphson scheme and eventually combined with other constraints, including the Eckart conditions. An example is also given.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540070410
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  • 8
    Electronic Resource
    Electronic Resource
    An ab initio distributed multipole study of the electrostatic potential around an undecapeptide cyclosporin derivative and a comparison with point charge electrostatic models (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 552-567 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: An SCF calculation has been performed on C63H113N11O12, a derivative of the immuno-suppressive drug cyclosporin, using a 3-21G basis set and a Direct SCF method. A distributed multipole analysis has been performed on the resulting charge density to give a set of multipoles at each atomic site, which are used to calculate the electrostatic potential around the molecule. The potential maxima and minima on the accessible surface of the molecule are compared with those predicted using the corresponding Mulliken charges, and also using a potential-derived point-charge model based on the force-field of Kollman et al. The Mulliken charges give a misleading picture of the electrostatic potential around this peptide. The potential-derived charges give results which are in far better agreement with the ab initio distributed multipole model, despite being derived from calculations on smaller molecules with different basis sets and geometries. The limitations of point-charge models for describing the electrostatic interactions of polypeptides are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540100412
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  • 9
    Electronic Resource
    Electronic Resource
    A molecular mechanics (MM2) study of Furan, Thiophene, and related compounds (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 10 (1989), S. 635-647 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The molecular mechanics calculations reported earlier for nitrogen heterocycles have now been extended to include the title compounds, and related molecules. It is in general possible to calculate these structures with an accuracy that compares favorably with experiment.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540100506
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  • 10
    Electronic Resource
    Electronic Resource
    Hamiltonian dynamics of chemical reactions. Consecutive first-order reactions and reactions possessing one autocatalytic intermediatePresented at the Symposium on Computation and Mathematical Chemistry, Saskatoon, Canada, June 1-4, 1986. (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 8 (1987), S. 744-751 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: A recently proposed Hamiltonian approach to phenomenological chemical kinetics [T. Georgian and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 10, 331 (1983); T. Georgian, J.M. Halpin, and G.L. Findley, Int. J. Quantum Chem., Quantum Biol. Symp. 11, 347 (1984)] is applied to all consecutive first-order, single-step reactions, and to all reactions possessing one autocatalytic intermediate. The reaction Hamiltonians presented are shown to be consistent with the phenomenological rate equations and the relationship between reaction form and the form of the reaction potential is discussed. In particular, we show: (1) that the interaction between consecutive reactions manifests itself as a coupling term in the reaction potential, a term which may be eliminated via transition to “normal reaction coordinates” for the chemical system; and (2) that coupled sets of autocatalytic reactions give rise to coupling terms in the reaction Hamiltonian which are characteristic of the reaction mechanism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540080519
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