Chemistry Department, University of California, Irvine, California 92697, USA.
J Chem Phys. 2011 Oct 21;135(15):154106. doi: 10.1063/1.3651473.
The variational Gaussian wavepacket (VGW) approximation provides an alternative to path integral Monte Carlo for the computation of thermodynamic properties of many-body systems at thermal equilibrium. It provides a direct access to the thermal density matrix and is particularly efficient for Monte Carlo approaches, as for an N-body system it operates in a non-inflated 3N-dimensional configuration space. Here, we greatly accelerate the VGW method by retaining only the relevant short-range correlations in the (otherwise full) 3N × 3N Gaussian width matrix without sacrificing the accuracy of the fully coupled VGW method. This results in the reduction of the original O(N(3)) scaling to O(N(2)). The fast-VGW method is then applied to quantum Lennard-Jones clusters with sizes up to N = 6500 atoms. Following Doye and Calvo [JCP 116, 8307 (2002)] we study the competition between the icosahedral and decahedral structural motifs in Ne(N) clusters as a function of N.
变分高斯波包 (VGW) 逼近为计算热平衡多体系统的热力学性质提供了一种替代路径积分蒙特卡罗的方法。它提供了对热密度矩阵的直接访问，并且对于蒙特卡罗方法特别有效，因为对于 N 体系统，它在非膨胀的 3N 维构形空间中运行。在这里，我们通过在（否则完整的）3N×3N 高斯宽度矩阵中仅保留相关的短程相关，而不牺牲完全耦合的 VGW 方法的准确性，极大地加速了 VGW 方法。这导致原始 O(N(3)) 标度降低到 O(N(2))。然后将快速-VGW 方法应用于尺寸高达 N = 6500 原子的量子 Lennard-Jones 团簇。遵循 Doye 和 Calvo [JCP 116, 8307 (2002)]，我们研究了 Ne(N)团簇中二十面体和十面体结构基元之间的竞争，作为 N 的函数。
