The present work outlines a new method for treatment of charge-dependent polarizability in semiempirical quantum models for use in combined quantum-mechanical/molecular mechanical simulations of biological reactions. The method addresses a major shortcoming in the performance of conventional semiempirical models for these simulations that is tied to the use of a localized minimal atomic-orbital basis set. The present approach has the advantages that it uses a density basis that retains a set of linear-response equations, does not increase the atomic-orbital basis, and avoids the problem of artificial charge transfer and scaling of the polarizability seen in related models that allow atomic charges to fluctuate. The model introduces four new atom-based parameters and has been tested with the modified neglect of differential overlap d-orbital Hamiltonian against and ions and shown to decrease the dipole moment and polarizability errors by factors of 2 and 10, respectively, with respect to density-functional results. The method performs impressively for a variety of charge states (from to ), and offers a potentially powerful extension in the design of next generation semiempirical quantum models for accurate simulations of highly charged biological reactions.
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Research Article| October 26 2005
Improvement of semiempirical response properties with charge-dependent response density
Timothy J. Giese;
Timothy J. Giese, Darrin M. York; Improvement of semiempirical response properties with charge-dependent response density. J. Chem. Phys. 22 October 2005; 123 (16): 164108. https://doi.org/10.1063/1.2080007
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