Because of its cubic symmetry, three deformation directions were selected in order to obtain the different constants of c11, c12 and c44.

• 本文采用ab initio方法，通过构造三种与张量元c11、c12和c44相关的晶胞变形，利用局域密度泛函计算晶胞变形时的结合能曲线，然后对所得的结合能曲线在平衡点处做二阶微商，求出c11、c12和c44。