Structural phase transitions, mechanical and electronic properties of ZrSe₂ under high pressures via the first-principles calculations

High-pressure phases of ZrSe₂ are predicted using the first-principles calculations combined with particle swarm optimization in the pressure range of 0 – 30 GPa. Three stable phases: the P3¯m1, C2/m and I4/mmm phases are identified, with the last two phases being predicted for the first time. The pressure-induced phase transition sequences are from the P3¯m1 phase to the C2/m phase, and then from the C2/m phase to the I4/mmm phase as the pressure increases. The related transition pressures are 3 GPa and 15 GPa, respectively. The thermal, dynamical and mechanical stabilities along with physical properties of these phases are investigated. In addition, the electronic band structures reveal that pressure-induced semiconductor-semimetal-metal transition occurs along with the structural phase transitions. Both the P3¯m1 and C2/m phases exhibit good catalytic activity in the hydrogen evolution reaction, calling for further experimental studies to verify.