利用第一性原理方法研究CuXSe_2(X=B,Al,Ga,In,Tl)力学性质

A study on mechanical properties of CuXSe_2(X=B,Al,Ga,In,Tl)by the first-principle calculations

在广义梯度近似(GGA)和局域密度近似(LDA)下,采用第一性原理方法研究CuXSe2(X=B,Al,Ga,In,Tl)晶体结构的稳定性和力学性质.分析CuXSe2(X=B,Al,Ga,In,Tl)结构的晶格常数,弹性常数,体积模量,剪切模量,杨氏模量,泊松比,对比各材料的力学性质变换规律.计算结果表明,根据力学稳定判据,在零温零压下,CuXSe2(X=B,Al,Ga,In,Tl)的晶体结构是力学稳定的.经过同主族替换,发现晶格常数越大,体弹性模量就越小.这可以解释为X离子半径逐渐增大,晶格常数逐渐增加,晶体的可压缩性也增加.另外,CuTlSe2的剪切模量最小,不容易发生剪切形变.CuBSe2的杨氏模量最大,其刚度最高.由Pugh经验关系可知CuXSe2(X=B,Al,Ga,In,Tl)均属于韧性材料.

The stability of crystal structures and mechanical properties of CuXSe2 （X=B,Al,Ga,In,Tl） have been investigated by first-principles method within the generalized gradient approximation （GGA） and local density approximation （LDA）.Lattice constants,bulk modulus,shear modulus,Young’s modulus and poisson’s ratio of CuXSe2 （X=B,Al,Ga,In,Tl）are analyzed.The results show that CuXSe2 （X=B,Al,Ga,In,Tl）crystals are mechanically stable at zero temperature and zero pressure by the standard of crystal mechanical stability.The lattice constants and compressibility with the increasing ionic radius.In addition,shear modulus of CuTlSe2 is minimum,which indicates that CuTlSe2 is not easily deformed.Young’s modulus of CuBSe2 is maximum,indicating that it has highest stiffness. Based on Pugh empirical relationship,it is found that the compounds of CuXSe2 （X=B,Al,Ga,In,Tl） are of ductile materials.