Department of Chemistry , University of Washington , Seattle , Washington 98195 , United States.
J Phys Chem A. 2019 Sep 19;123(37):8063-8070. doi: 10.1021/acs.jpca.9b06444. Epub 2019 Sep 5.
An efficient and accurate approach for using diffusion Monte Carlo (DMC) to study molecular clusters is described and applied to an investigation of (HO) with = 1, 2, 3. In this approach, importance sampled DMC is used to describe the intramolecular degrees of freedom of the water monomers. The intermolecular degrees of freedom are treated using standard unguided DMC approaches. This hybrid approach allows us to use significantly smaller simulations to obtain converged zero-point energies and ground state wave functions than would be required for a fully unguided simulation of the same system. We demonstrate the efficiency, accuracy, and utility of this approach through a study of nine isotopologues of water trimer, focusing on how the ground state probability amplitude for these clusters samples the various low-energy minima on the potential surface.
描述了一种使用扩散蒙特卡罗（DMC）研究分子簇的高效准确方法，并将其应用于（HO）的研究，其中 = 1、2、3。在这种方法中，使用重要性抽样 DMC 来描述水分子单体的分子内自由度。使用标准无引导 DMC 方法处理分子间自由度。这种混合方法使我们能够使用明显更小的模拟来获得收敛的零点能和基态波函数，而不是对相同系统进行完全无引导模拟所需的模拟。我们通过对水三聚体的九个同位素的研究证明了这种方法的效率、准确性和实用性，重点研究了这些簇的基态概率振幅如何在势能表面上采样各种低能极小值。
