First-principles calculations of electron-phonon coupling in NaSnSb: buckling and pressurization

Abstract In this paper, the electron-phonon coupling (EPC) properties of topological material NaSnSb has been explored, whose low phonon branch dominates the EPC constant λ . NaSnSb can remain the strength of its EPC with a slight compression of the distance of the Na and Sb atoms along the z -axis ( z Na–Sb ), while further compression or stretching would destroy the strength of its EPC. By pressing, in the pressure range of 2 GPa, the superconducting transition temperature ( T c ) of NaSnSb behaves similar to that of FeSe in the same pressure range, with a local minimum at 1 GPa and a maximum at 1.5 GPa. Both compressing z Na–Sb and pressure lead to phonon softening of NaSnSb. The phonon softening induced by compressing z Na–Sb is three-dimensional, whereas the phonon softening induced by compression is two-dimensional.