As one of the simplest compounds, cubic binary alkali metal hydrides are excellent research samples for further understanding the metallization, stability, and superconductivity of hydrogen-based superconductors. This paper is based on first principles calculations using density functional theory, and investigates in detail the metallization, stability, and superconductivity of NaCl and CsCl type of MH (Li, Na, K, Rb, Cs) under pressure. This paper provides the metallization pressure range and stable pressure range of MH. The calculation results indicate that the introduction of large radius metal elements from the same main group can effectively reduce the metallization pressure of the material, and at the same time lower the phase transition pressure point from MH-B1 to MH-B2 type. Finally, the research in this paper indicates that under pressure, the low-frequency phonon softening and the sustained softening of the high-frequency phonon partial Kohn anomaly point result in the material exhibiting a higher superconducting temperature as it approaches unstable pressure.
Li et al. (Tue,) studied this question.