High-efficiency computational methodologies for electronic properties and structural characterization of Ge-Sb-Te based phase change materials

Abstract

Theoretical simulation to phase change materials such as Ge-Sb-Te has suffered from two methodology issues. On the one hand, there is a lack of efficient band gap correction method for density functional theory, which is suitable for these materials in both crystalline and amorphous phases, though the computational complexity should be kept at the local density approximation level. On the other hand, analysis of the coordination number in amorphous phases relies on an integration involving the radial distribution function, which adds to the complexity. In this work, we find that the shell DFT-1/2 method offers an overall band gap accuracy for phase change materials comparable to HSE06 hybrid functional, though its computational cost is around three orders of magnitude lower. Moreover, the mixed length-angle coordination number theory enables calculating the coordination numbers in the amorphous phase directly from the structure, with definite outcomes. The two methodologies could be helpful for high throughput simulation of phase change materials.