Liu Jian, Pedroza Luana S, Misch Carissa, Fernández-Serra Maria V, Allen Philip B
Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800, USA.
J Phys Condens Matter. 2014 Jul 9;26(27):274204. doi: 10.1088/0953-8984/26/27/274204. Epub 2014 Jun 17.
We present total energy and force calculations for the (GaN)1-x(ZnO)x alloy. Site-occupancy configurations are generated from Monte Carlo (MC) simulations, on the basis of a cluster expansion model proposed in a previous study. Local atomic coordinate relaxations of surprisingly large magnitude are found via density-functional calculations using a 432-atom periodic supercell, for three representative configurations at x = 0.5. These are used to generate bond-length distributions. The configurationally averaged composition- and temperature-dependent short-range order (SRO) parameters of the alloys are discussed. The entropy is approximated in terms of pair distribution statistics and thus related to SRO parameters. This approximate entropy is compared with accurate numerical values from MC simulations. An empirical model for the dependence of the bond length on the local chemical environments is proposed.
我们给出了(GaN)1-x(ZnO)x合金的总能量和力的计算结果。基于先前研究中提出的团簇展开模型，通过蒙特卡罗(MC)模拟生成了占位构型。使用432个原子的周期性超胞，通过密度泛函计算，对于x = 0.5时的三种代表性构型，发现了幅度惊人的局部原子坐标弛豫。这些用于生成键长分布。讨论了合金的构型平均成分和温度相关的短程有序(SRO)参数。熵是根据对分布统计近似得出的，因此与SRO参数相关。将这种近似熵与MC模拟的精确数值进行了比较。提出了一个键长对局部化学环境依赖性的经验模型。
