First-principles study of thermal expansion and thermomechanics of group-V monolayers: blue phosphorene, arsenene, and antimonene

Using first-principles calculations based on quasiharmonic approximation (QHA), we systematically investigate the vibrational properties, thermal expansion and thermomechanics properties of three monoatomic group-V monolayers with honeycomb structure: blue phosphorene, arsenene and antimonene. It is found antimonene shows negative thermal expansion in the temperature range studied, while blue phosphorene and arsenene display small positive thermal expansion at high temperature. The physical mechanisms of their different thermal properties are explored. The results of Grüneisen theory are also exhibited for comparison, and the similarities and differences are studied. It is concluded the discrepancies arise from the high order anharmonicity of phonons.