Theoretical Study of Pressure‐Loading Way Dependence of Phase Transition Behaviors of Bulk 1T‐VSe 2

First‐principles calculations study pressure‐induced phase transitions in bulk 1T‐VSe 2 . Under hydrostatic compression at around 4 GPa, the1T phase undergoes an isostructural transition with anisotropic lattice contraction. Under hydrostatic pressure (1–8 GPa), at least 8 GPa uniaxial pressure can trigger the 1T → charge density wave (CDW)‐1∼8 → CDW‐9 transitions, in which the in‐plane double zigzag chains and trimers of vanadium atoms . The CDW‐9 ( C 2/ m (6)) → P 2 1 / m transition is achieved under combined hydrostatic and uniaxial pressure (at least 15 GPa) along the b ‐axis. The vanadium trimers of CDW‐9 configuration progressively decouple into dimers layer by layer and then the dimers appear in the whole layers of monoclinic P 2 1 / m phase. The 1T → 3R ( R ‐3 m ) transition can be achieved under shear stress at around 1.5 GPa along [−110] 1T direction without the assistance of hydrostatic pressure. Under at least shear stress (9 GPa) along the b ‐axis plus hydrostatic pressure of around 10 GPa, the six‐coordinated C 2/ m (6) phase transforms into the eight‐coordinated C 2/ m (8) phase. The shear stress at around 12 GPa along the c ‐axis transforms the 1T‐phase structure into a new Immm phase. The 1T → CDW‐9 ( C 2/ m (6)) → P 2 1 / m , C 2/ m (6) → C 2/ m (8), and 1T → Immm transitions are reconstructive‐type transition.