Scalar-product cluster variation method layer formulation for the irregular tetrahedron cluster in bcc lattices

The scalar-product cluster variation method (SP-CVM) for calculation of antiphase boundary (APB) energies has been extended for application to {001} APBs in the body-centered cubic lattice using the irregular tetrahedron cluster approximation. In order to do so, the proof of the SP-CVM relation has been updated to include the cases where the domain interface consists of more than one plane of atoms (i.e., it consists of a layer of atoms). The algorithm has been developed for the cases of thermal APBs with APB vectors a0A2<100> and a0A2/2<111>. It is then applied, as an illustration, to the determination of APB energies in isothermal calculations in the Fe-Al system