关键词: superconductivity, first-principles calculations, hydrogen-rich compounds

Abstract: Obtaining room-temperature superconductors has long been a research hotspot in the field of condensed matter physics. Previous studies have shown that doping strategies can effectively enhance the superconducting properties of materials. In this work, we employed first-principles calculations combined with the particle swarm optimization method to explore the structural possibilities of the Ca-doped As-H ternary system and to calculate the electronic and superconducting properties of the newly identified structures. Two thermodynamically stable hydrides were found under high pressure. The $P$4/nmm-Ca$_{2}$AsH$_{4}$ phase remains thermodynamically stable within the pressure range of 90-200 GPa, while the Cc-Ca$_{2}$AsH$_{6}$ phase exhibits stability over a broader range of 79-200 GPa. Electron-phonon coupling analysis indicates that the superconducting critical temperatures ($T_{\rm c}$) of $P$4/nmm-Ca$_{2}$AsH$_{4}$ and Cc-Ca$_{2}$AsH$_{6}$ are 11 K and 16 K at 100 GPa, respectively. The incorporation of Ca significantly reduces the thermodynamic stability pressure of As-H compounds with higher hydrogen content, thereby improving their synthetic accessibility.

Key words: superconductivity, first-principles calculations, hydrogen-rich compounds