On the interfragment exchange in the X-pol method

Alessandro Cembran, Peng Bao, Yingjie Wang, Lingchun Song, Donald G. Truhlar, Jiali Gao

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26 Scopus citations


The inclusion of exchange repulsion terms in the explicit polarization (X-Pol) model is examined by antisymmetrizing the X-Pol Hartree product wave function; this yields X-Pol with full eXchange, called X-Pol-X. When the monomers are treated by Hartree-Fock theory, this calculation can be accomplished by using the formalism of block-localized wave functions (BLW) that has been used in a variety of applications. In this case the block-localized structure in the X-Pol-X wave function allows for decomposition of the full Fock matrix of a dimension of M blocks into M smaller Fock matrices. The method is illustrated by considering two trimer structures of water clusters, and it is found that the total exchange repulsion energies in these hydrogen-bonding test cases are adequately treated andsto a good approximationsare pairwise additive. We also present a formalism to yield a simplified Fock matrix by making use of the neglect of interfragment differential overlap (NIDO) approximation, which is less severe than the neglect of diatomic differential overlap (NDDO) approximation.

Original languageEnglish (US)
Pages (from-to)2469-2476
Number of pages8
JournalJournal of Chemical Theory and Computation
Issue number8
StatePublished - Aug 10 2010

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