Development of an interatomic potential for Ga<i>x</i>In1−<i>x</i>P and its application in describing the mechanical, structural, vibrational, and thermal properties as a function of atomic ordering

Abstract

Molecular dynamics simulations are employed to investigate the pseudoternary alloy GaxIn1−xP using a transferable interatomic potential fitted to the experimental properties of the binary compounds InP (x=0) and GaP (x=1). Structural, thermomechanical, and vibrational properties are predicted across all compositions for both ordered and disordered atomic configurations, and the results show good agreement with available experimental data. The lattice parameter and cohesive energy of the zinc-blende phase follow a nearly Vegard’s law trend in both ordered and disordered cases. In contrast, the cohesive energy of the wurtzite phase, as well as the elastic constants and surface energy, exhibit noticeable nonlinear behavior under disorder, deviating from Vegard’s law. The evolution of first-neighbor distances with composition was compared with an extended x-ray absorption fine structure data, showing excellent agreement. Other properties, such as specific heat and melting temperature, display nonlinearity in both ordered and disordered configurations, with the latter matching the expected experimental behavior. Density of states analysis reveals two-mode behavior in the ordered case, which is partially masked by disorder. The frequencies of longitudinal and transverse modes at high-symmetry points X and L show generally good agreement with experimental results.