Direct anharmonic correction method by molecular dynamics

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• 作者：Zhong-Li Liu^a ; ^{zl.liu@163.com} ; Rui Li^a ; Xiu-Lu Zhang^b ; Nuo Qu^a ; Ling-Cang Cai^c
• 关键词：Anharmonic corrections ; Molecular dynamics ; Thermal properties ; Equation of states
• 刊名：Computer Physics Communications
• 出版年：2017
• 出版时间：April 2017
• 年：2017
• 卷：213
• 期：Complete
• 页码：122-129
• 全文大小：831 K
• 卷排序：213

文摘

The quick calculation of accurate anharmonic effects of lattice vibrations is crucial to the calculations of thermodynamic properties, the construction of the multi-phase diagram and equation of states of materials, and the theoretical designs of new materials. In this paper, we proposed a direct free energy interpolation (DFEI) method based on the temperature dependent phonon density of states (TD-PDOS) reduced from molecular dynamics simulations. Using the DFEI method, after anharmonic free energy corrections we reproduced the thermal expansion coefficients, the specific heat, the thermal pressure, the isothermal bulk modulus, and the Hugoniot PP–VV–TT relationships of Cu easily and accurately. The extensive tests on other materials including metal, alloy, semiconductor and insulator also manifest that the DFEI method can easily uncover the rest anharmonicity that the quasi-harmonic approximation (QHA) omits. It is thus evidenced that the DFEI method is indeed a very efficient method used to conduct anharmonic effect corrections beyond QHA. More importantly it is much more straightforward and easier compared to previous anharmonic methods.