Department of Chemistry, University of California, Irvine, California 92617, USA.
J Chem Phys. 2018 Sep 14;149(10):104305. doi: 10.1063/1.5050410.
The solid-solid and melting transitions that occur in Lennard-Jones LJ clusters have been both fascinating and challenging for the computational physics community over the last several decades. A number of attempts to extend these studies to the quantum case have also been made. Particularly interesting is the exploration of the parallel between the thermally induced and quantum-induced transitions. Yet, both numerically accurate and systematic studies of the latter are still lacking. In this paper, we apply the diffusion Monte Carlo method to the especially difficult case of LJ. Starting with the truncated octahedral global minimum configuration, as the de Boer quantum delocalization parameter Λ increases, the system undergoes two consecutive solid-solid transitions, switching to anti-Mackay configurations. At sufficiently large values of Λ, the cluster is completely "melted," which is manifested by delocalization of the ground state wavefunction over a very large number of minima that represent several structural motifs.
在过去的几十年里， Lennard-Jones (LJ) 团簇中的固-固转变和熔融转变一直令计算物理界着迷和具有挑战性。也有许多尝试将这些研究扩展到量子情况的尝试。特别有趣的是探索热诱导和量子诱导转变之间的平行关系。然而，后者的数值准确和系统研究仍然缺乏。在本文中，我们将扩散蒙特卡罗方法应用于 LJ 的特别困难的情况。从截断的八面体全局最小构型开始，随着 de Boer 量子离域参数 Λ 的增加，系统经历了两个连续的固-固转变，转变为反 Mackay 构型。在足够大的 Λ 值下，团簇完全“熔化”，这表现为基态波函数在非常多的代表几种结构基元的极小值上的离域。
