二元fcc无序合金的晶格常数和体弹模量的第一性原理计算方法探究

Lattice Constant and Bulk Modulus of Binary Fcc Disordered Alloys studied by the First-principles Calculations

通过建立特殊准随机结构(SQS),采用第一性原理VASP程序,用两种不同的弛豫方法分别对二元fcc Ni-X(X=Al,Au,Cu,Ga,Mo,Pt,Ta,W)无序合金的晶格常数和体弹模量随成分的变化进行了计算。这两种弛豫方法分别是离子弛豫法和体积弛豫法。最终计算结果表明,两种计算方法所得的晶格常数和体弹模量非常相近。因此在计算二元无序合金的晶格常数和体弹模量时,可以只做体积弛豫。这不仅大大简化了计算步骤,而且能够保持点阵的对称性,为计算二元合金的体积和体弹模量提供了准确高效的计算方法。

By establishing the Special Quasirandom Structures （SQS）, the lattice constant and bulk modulus of fcc Ni- X （ X = Al, Au, Cu, Ga, Mo, Pt, Ta, W） disordered alloy were calculated using the first-principles calculation program-VASP. Two kinds of different relaxation methods were used： ion relaxation method and volume relaxation method. By comparing the final computation results, it was found that the lattice constant and bulk modulus calculated by the two methods were very close. The volume relaxation scheme kept the lattice symmetry and provided a simpler and efficient way to calculate the volume and bulk modulus of binary alloys.