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arXiv 1004.4513cond-mat.mtrl-sci
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表面吸附和脱附的从头算统计力学:II。核量子效应

Ab initio statistical mechanics of surface adsorption and desorption: II. Nuclear quantum effects

D. Alfe`, M. J. Gillan

摘要:

我们展示了如何量子统计力学的路径积分公式可以用来构建实用的{ \em从头计算}技术,用于计算吸附在表面上的分子的化学势,完全包含量子核效应。我们描述的技术是基于计算的潜在的平均力在一个选定的分子,并概括了最近开发的技术为经典的核。本文基于密度泛函理论,采用广义梯度交换关联泛函,对H $_2$ O在MgO~(001)表面低覆盖度的情况进行了计算.我们注意到,非常高的振动频率的H $_2$ O分子通常需要非常大量的时间片(珠)在路径积分计算,但我们表明,这一要求可以显着减少采用热力学积分的想法相对于珠的数量。通过对一组简单模型体系的计算,证明了我们对H $_2$ O/MgO~(001)体系路径积分计算的正确性和有效性。

英文摘要:

We show how the path-integral formulation of quantum statistical mechanics can be used to construct practical {\em ab initio} techniques for computing the chemical potential of molecules adsorbed on surfaces, with full inclusion of quantum nuclear effects. The techniques we describe are based on the computation of the potential of mean force on a chosen molecule, and generalise the techniques developed recently for classical nuclei. We present practical calculations based on density functional theory with a generalised-gradient exchange-correlation functional for the case of H$_2$O on the MgO~(001) surface at low coverage. We note that the very high vibrational frequencies of the H$_2$O molecule would normally require very large numbers of time slices (beads) in path-integral calculations, but we show that this requirement can be dramatically reduced by employing the idea of thermodynamic integration with respect to the number of beads. The validity and correctness of our path-integral calculations on the H$_2$O/MgO~(001) system are demonstrated by supporting calculations on a set of simple model systems for which quantum contributions to the free energy are known exactly from analytic arguments.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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