Dispersion treatment for NDDO-based semiempirical MO techniques

Authors

  • Bodo Martin,

    1. Computer-Chemie-Centrum der Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Naegelsbachstrasse 25, 91052 Erlangen, Germany
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  • Timothy Clark

    Corresponding author
    1. Computer-Chemie-Centrum der Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Naegelsbachstrasse 25, 91052 Erlangen, Germany
    • Computer-Chemie-Centrum der Friedrich-Alexander-Universitaet Erlangen-Nuernberg, Naegelsbachstrasse 25, 91052 Erlangen, Germany
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Abstract

We introduce an additional term to treat dispersion in NDDO-based semiempirical molecular orbital techniques. The dispersion energy is calculated using additive “atomic orbital” polarizability tensors determined with our modified version of Rivail's variational technique. Frequency-dependent polarizabilities can be obtained using Padé approximants, which proved more reliable than the Unsöld approximation or a Taylor-series approach. Dispersion energies are best calculated using the Slater–Kirkwood modification of the London formula, although they can also be obtained using the Casimir–Polder approach with frequency-dependent polarizabilities. A test parameterization using MNDO as the semiempirical technique indicated that weak interactions can be reproduced satisfactorily. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006

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