Temperature-dependent interatomic forces
Temperature-dependent interatomic forces
复制标题
DOI：
10.1080/01418618908219278
复制
发表时间：
1989-08
影响因子：
1.6
通讯作者：
A. Sutton
中科院分区：
文献类型：
--
作者：
A. Sutton
本文提出了一种在有限温度下优化晶体中缺陷的热平均结构的方法。其基本思想是增加原子间的力量，适用于与温度相关的贡献，从自由能在有限温度下的最小化所产生的OK。用分子静力学程序可以得到缺陷的结构和热力学性质。自由能表示在谐波近似，但由于在O K原子间的潜力是非谐的，有一个额外的温度依赖的力所产生的振动自由能。同一项引起完美晶体的热膨胀。声子局域态密度采用二阶矩近似。投影到个别原子网站的热力学功能，然后表示解析。当振动自由能被微分时，所产生的力在性质上是N体的，即使对于成对的原子间相互作用也是如此。
Abstract A method of optimizing the thermally averaged structure of a defect in a crystal at a finite temperature is presented. The basic idea is to augment the interatomic forces that apply at OK with temperature-dependent contributions that arise from the minimization of the free energy at a finite temperature. The structure and thermodynamic properties of the defect can then be obtained with a molecular statics program. The free energy is expressed within the harmonic approximation, but since the interatomic potential at O K is anharmonic, there is an additional temperature-dependent force arising from the vibrational free energy. The same term gives rise to the thermal expansion of the perfect crystal. A second-moment approximation is applied to the phonon local density of states. Projections of thermodynamic functions onto individual atomic sites are then expressed analytically. When the vibrational free energy is differentiated, the resulting force is N-body in nature even for a pairwise interatomic...