Comparison of the Charge Density Wave Transition in Monolayer 1T-TaS₂ and 1T-TaSe₂ from First Principle

By performing ab initio molecular dynamics (AIMD) simulations, we systematically compare the structural and electronic properties of monolayer 1T-TaS2 and 1T-TaSe2 as a function of temperature. A much higher commensurate charge density wave (CCDW) transition temperature in 1T-TaSe2 is theoretically rationalized. The capability of 1T-TaSe2 in accommodating larger CCDW fluctuations lead to the emergence of a CCDW metal phase, which is absent in 1T-TaS2. The richer phase diagram, especially the metal-to-insulator transition (MIT) within the CCDW phase, makes monolayer 1T-TaSe2 a promising candidate for nanoscale functional applications such as switching devices.