Analysis of order-disorder transition in V-H system by the cluster variation method

推导了bcc结构八面体近似中聚类变分法的构型熵公式，并将聚类变分法应用于V-H体系的有序-无序跃迁分析。第三和第四近邻对v_ 3和v_ 4的相互作用稳定了有序相，并对跃迁有强烈的影响。两相区的窄宽度表明有序-无序转变为一级，但非常接近二级。

The configurational entropy formula of the Cluster Variation Method in the octahedron approximation for the bcc structure has been derived, and the CVM has been applied to the analysis on the order-disorder transition in the V-H system. It has been confirmed that both the third and fourth nearest neighbor pair interactions, v_ 3 and v_ 4, stabilize the ordered phase and strongly affect the transition. The narrow width of the two phase region show that the order-disorder transition is the first order, but is extremely close to the second order.