First-principles LCAO study of the low- and room-temperature phases of CdPS₃

The electronic and atomic structure of a bulk 2D layered van-der-Waals compound CdPS₃ was studied in the low (R3) and room (C2/m) temperature phases using first-principles calculations within the periodic linear combination of atomic orbitals method with hybrid meta exchange-correlation M06 functional. The calculation results reproduce well the experimental crystallographic parameters. The value of the indirect band gap E_g = 3.4 eV for the room-temperature monoclinic C2/m phase is close to the experimental one, while the indirect band gap E_g = 3.3 eV was predicted for the low-temperature trigonal R3 phase. The effect of hydrostatic pressure on the band gap in both phases was studied in the pressure range from 0 to 40 GPa. In both cases, the pressure dependence of the band gap passes through a maximum, but at different pressures. In the R3 phase, the band gap reaches its maximum value of ∼4 eV at ∼30 GPa, whereas in the C2/m phase, the maximum value of ∼3.6 eV is reached already at ∼8 GPa.