Ab initio calculation of the stability of one-dimensional long-period structures in the Cu₃Pd compound

Abstract

The relative stabilities of L1₂, D0₂₂, D0₂₃ and several one-dimensional (1D) long period structures (LPSs) in the Cu₃Pd intermetallic compound are investigated employing the Vienna ab initio simulation package. The energy effects due to the tetragonal distortion of the D0₂₂ and D0₂₃ structures and other 1D LPSs are small, and those due to the cell internal displacements of the atoms in the LPSs are negligible. With distortion, the <3> structure is found to be the ground state; however, the structures <4> and <43> are rather close in energy to this ground state. The energy results are discussed in the framework of the axial next-nearest-neighbour Ising model. Predictions of the energy differences between series of 1D LPSs and the L1₂ structure are provided. The (001) antiphase boundary energy is also determined using the same model.