CALANIE: Anisotropic elastic correction to the total energy, to mitigate the effect of periodic boundary conditions

CALANIE (CALculation of ANIsotropic Elastic energy) computer program evaluates the elastic interaction correction to the total energy of a localized object, for example a defect in a material simulated using an ab initio or molecular statics approach, resulting from the use of periodic boundary conditions. The correction, computed using a fully elastically anisotropic Green’s function formalism, arises from the elastic interaction between a defect and its own periodically translated images. The long-range field of elastic displacements produced by the defect is described in the elastic dipole approximation. Applications of the method are illustrated by two case studies, one involving an ab initio investigation of point defects and vacancy migration in FCC gold, and another a molecular statics simulation of a dislocation loop. We explore the convergence of the method as a function of the simulation cell size, and note the significance of taking into account the elastic correction in the limit where the size of the defect is comparable with the size of the simulation cell.

CALANIE（CALculation of ANIsotropic Elastic energy）程序可计算局域对象总能量的弹性相互作用修正项，此类局域对象包括采用从头算（ab initio）或分子静力学（molecular statics）方法模拟的材料缺陷，该修正项由周期性边界条件的使用所引发。该修正项采用完全弹性各向异性格林函数（Green’s function）形式体系进行计算，源于缺陷与其周期性平移镜像之间的弹性相互作用。缺陷所产生的弹性位移长程场采用弹性偶极近似（elastic dipole approximation）进行描述。本方法的应用通过两项案例研究予以阐释：其一为针对面心立方（Face-Centered Cubic，FCC）金中点缺陷与空位迁移的从头算研究，其二为位错环的分子静力学模拟。本文探究了该方法随模拟晶胞尺寸变化的收敛特性，并指出当缺陷尺寸与模拟晶胞尺寸相当的极限情形下，考虑弹性修正项具备重要研究意义。