Pressure-induced structural, electronic, and superconducting phase transitions in TaSe₃

Abstract TaSe 3 has garnered significant research interests due to its unique quasi-one-dimensional crystal structure, which gives rise to distinctive properties. Using crystal structure search and first-principles calculations, we systematically investigated the pressure-induced structural and electronic phase transitions of quasi-one-dimensional TaSe 3 up to 100 GPa. In addition to the ambient pressure phase ( P 2 1 / m -I), we identified three high-pressure phases: P 2 1 / m -II, Pnma , and Pmma . For the P 2 1 / m -I phase, the inclusion of spin–orbit coupling (SOC) results in significant SOC splitting and changes in the band inversion characteristics. Furthermore, band structure calculations for the three high-pressure phases indicate metallic natures, and the electron localization function suggests ionic bonding between Ta and Se atoms. Our electron–phonon coupling calculations reveal a superconducting critical temperature of approximately 6.4 K for the Pmma phase at 100 GPa. This study provides valuable insights into the high-pressure electronic behavior of quasi-one-dimensional TaSe 3 .