Free energies of crystals computed using Einstein crystal with fixed center of mass and differing spring constants.
Free energies of crystals computed using Einstein crystal with fixed center of mass and differing spring constants.
复制标题
使用具有固定质心和不同弹簧常数的爱因斯坦晶体计算晶体的自由能。
DOI：
10.1063/5.0044833
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
B. Peters
中科院分区：
文献类型：
--
作者：
V. Khanna;J. Anwar;D. Frenkel;M. Doherty;B. Peters
如Polson等人的先前工作[J.Chem.Phys.112，5339-5342（2000）]所示，使用质量中心约束计算的晶体自由能需要有限尺寸校正。他们的参考系是一个具有相等弹簧常数的爱因斯坦晶体。在本文中，我们将Polson等人的工作[J.Chem.Phys.112，5339-5342（2000）]扩展到不同弹簧常数的情况。这种推广方法便于约束不同质量原子的晶体的质心，并有助于优化自由能的计算。为了测试的理论，我们比较的自由能的LiI和NaCl晶体的计算与不同的弹簧常数计算使用相同的弹簧常数。使用这些质心有限尺寸修正，我们计算这些晶体的真实自由能为不同的系统尺寸，以消除固有的有限尺寸效应。这些计算有助于证明这些有限尺寸修正相对于其他贡献的晶体的绝对自由能的大小。
Free energies of crystals computed using a center of mass constraint require a finite-size correction, as shown in previous work by Polson et al. [J. Chem. Phys. 112, 5339-5342 (2000)]. Their reference system is an Einstein crystal with equal spring constants. In this paper, we extend the work of Polson et al. [J. Chem. Phys. 112, 5339-5342 (2000)] to the case of differing spring constants. The generalization is convenient for constraining the center of mass in crystals with atoms of differing masses, and it helps to optimize the free energy calculations. To test the theory, we compare the free energies of LiI and NaCl crystals from calculations with differing spring constants to those computed using equal spring constants. Using these center of mass finite size corrections, we compute the true free energies of these crystals for different system sizes to eliminate the intrinsic finite-size effects. These calculations help demonstrate the size of these finite-size corrections relative to other contributions to the absolute free energy of the crystals.