Numerical Fitting of Molecular Properties to Hermite Gaussians

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• 作者：G. André ; s Cisneros ; Dennis Elking ; Jean-Philip Piquemal ; Thomas A. Darden
• 刊名：Journal of Physical Chemistry A
• 出版年：2007
• 出版时间：November 29, 2007
• 年：2007
• 卷：111
• 期：47
• 页码：12049 - 12056
• 全文大小：74K
• 年卷期：v.111,no.47(November 29, 2007)
• ISSN：1520-5215

文摘

A procedure is presented to fit gridded molecular properties to auxiliary basis sets (ABSs) of Hermite Gaussians,analogous to the density fitting (DF) method (Dunlap; et al. J. Chem. Phys. 1979, 71, 4993). In this procedure,the ab initio calculated properties (density, electrostatic potential, and/or electric field) are fitted via a linear-or nonlinear-least-squares procedure to auxiliary basis sets (ABS). The calculated fitting coefficients fromthe numerical grids are shown to be more robust than analytic density fitting due to the neglect of the corecontributions. The fitting coefficients are tested by calculating intermolecular Coulomb and exchangeinteractions for a set of dimers. It is shown that the numerical instabilities observed in DF are caused by theattempt of the ABS to fit the core contributions. In addition, this new approach allows us to reduce thenumber of functions required to obtain an accurate fit. This results in decreased computational cost, which isshown by calculating the Coulomb energy of a 4096 water box in periodic boundary conditions. Using atomcentered Hermite Gaussians, this calculation is only 1 order of magnitude slower than conventional atom-centered point charges.