Comparison of two calculation models for high entropy alloys: Virtual crystal approximation and special quasi-random structure

We investigated the suitable range of virtual crystal approximation (VCA) and special quasi-random structure (SQS) for estimating lattice constants (LCs) of high entropy alloys (HEAs). For the HEAs composed of the atoms with similar atomic radius and electronic configuration, such as FeCoNiCr combined with Cu or V, the LCs obtained by SQS and VCA methods are close to each other. When combined with atoms with quite different atomic radius and electronic configuration, such as Nb, Ge or Ti, there is obvious lattice distortion in the SQS supercell, and the LCs of VCA models are quite different from that of SQS models. The SQS method can be replaced by VCA when estimating LCs of HEAs composed of atoms with similar properties, which is helpful to increase computation efficiency.