The Loss of Size Sensitivity in para -Hydrogen Clusters Due to the Strong Quantum Delocalization
The Loss of Size Sensitivity in para -Hydrogen Clusters Due to the Strong Quantum Delocalization
复制标题
由于强量子离域而导致对氢团簇尺寸敏感性的丧失
DOI：
10.1021/acs.jpca.0c07107
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Mandelshtam, Vladimir A.
中科院分区：
文献类型：
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作者：
Kohno, Bridgett H.;Mandelshtam, Vladimir A.
对氢(PH2)原子团簇一直是众多计算研究的焦点。这些研究最初是出于观察到超流的可能性，也揭示了(PH2)N丰富而复杂的结构性质。然而，它们的结构分析通常仅限于通过计算它们的基态能量En和化学势μN=en-En-1作为n的函数来识别“魔数团簇”。其次是基于定义不明确的径向密度分布的结构分析。然而，令人惊讶的是，文献中报道的关于大约N=25以上的团簇大小的结果之间存在显著的差异，这种模棱两可的情况直到现在还没有得到解决。在本文中，我们应用扩散蒙特卡罗方法来解决在N=24-28范围内团簇大小不一致的问题。在这里，我们试图避免基于高要求的能量计算的猜测，这些计算的数值精度具有模糊性。相反，我们专注于对基态波函数的直接和明确的结构分析，这支持了在所考虑的尺寸范围内团簇在结构上相同的结论。也就是说，至少在Rangen=24-28中没有魔数簇，这与以前的一些出版物所建议的相反。这种对氢原子团簇尺寸敏感性的缺乏是这些体系中强烈的量子离域效应的直接结果。
para-Hydrogen (pH2)Nclusters have been the focus of numerous computational studies. Originally motivated by the possibility of observing superfluidity, these studies also revealed rich and complex structural properties of (pH2)N. However, their structural analysis was typically limited to attempts to identify “magic number clusters” by computing their ground state energiesENand the chemical potential μN=EN–EN–1as a function ofN. This was followed by structural analysis based on an ill-defined radial density profile. Surprisingly, however, there were remarkable discrepancies between the results reported in the literature for cluster sizes beyond approximatelyN= 25, and this ambiguity remained unsettled until now. In the present paper, we apply the diffusion Monte Carlo method to resolve inconsistencies in cluster sizes within the range (N= 24–28). Here, we try to avoid speculations based on the highly demanding energy calculations whose numerical accuracy harbors ambiguity. Instead, we focus on the direct and unambiguous structural analysis of the ground state wavefunctions, which supports the conclusion that the clusters are structurally the same in the size range considered. That is, there are no magic number clusters at least in the rangeN= 24–28, contrary to what some of the previous publications have suggested. This lack of size sensitivity ofpara-hydrogen clusters is a direct consequence of the strong quantum delocalization in these systems.