Reactive Many-Body Expansion for a Protonated Water Cluster

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• 作者：Peter Pinski ; Gábor Csányi
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2014
• 出版时间：January 14, 2014
• 年：2014
• 卷：10
• 期：1
• 页码：68-75
• 全文大小：469K
• ISSN：1549-9626

文摘

We generalize the standard many-body expansion technique that is used to approximate the total energy of a molecular system to enable the treatment of chemical reactions by quantum chemical techniques. By considering all possible assignments of atoms to monomer units of the many-body expansion and associating suitable weights with each, we construct a potential energy surface that is a smooth function of the nuclear positions. We derive expressions for this reactive many-body expansion energy and describe an algorithm for its evaluation, which scales polynomially with system size, and therefore will make the method feasible for future condensed phase simulations. We demonstrate the accuracy and smoothness of the resulting potential energy surface on a molecular dynamics trajectory of the protonated water hexamer, using the Hartree鈥揊ock method for the many-body term and M酶ller鈥揚lesset theory for the low order terms of the many-body expansion.