Toward Chemical Accuracy in the Description of Ion–Water Interactions through Many-Body Representations. I. Halide–Water Dimer Potential Energy Surfaces
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- 作者：Pushp Bajaj ; Andreas W. Götz ; Francesco Paesani
- 刊名：Journal of Chemical Theory and Computation
- 出版年：2016
- 出版时间：June 14, 2016
- 年：2016
- 卷：12
- 期：6
- 页码：2698-2705
- 全文大小：549K
- 年卷期：0
- ISSN：1549-9626
文摘
Despite recent progress, a unified understanding of how ions affect the structure and dynamics of water across different phases remains elusive. Here, we report the development of full-dimensional many-body potential energy functions, called MB-nrg (Many-Body-energy), for molecular simulations of halide ion–water systems from the gas phase to the condensed phase. The MB-nrg potentials are derived entirely from “first-principles” calculations carried out at the F12 explicitly correlated coupled-cluster level including single, double, and perturbative triple excitations, CCSD(T)-F12, in the complete basis set limit. Building upon the functional form of the MB-pol water potential, the MB-nrg potentials are expressed through the many-body expansion of the total energy in terms of explicit contributions representing one-body, two-body, and three-body interactions, with all higher-order contributions being described by classical induction. The specific focus of this study is on the MB-nrg two-body terms representing the full-dimensional potential energy surfaces (PESs) of the corresponding H2O–X– dimers, with X–= F–, Cl–, Br–, and I–. The accuracy of the MB-nrg PESs is systematically assessed through extensive comparisons with results obtained using both ab initio models and polarizable force fields for energies, structures, and harmonic frequencies of the H2O–X– dimers.