Modulation of doping and biaxial strain on the transition temperature of the charge density wave transition in 1T-TiSe2

We study the effects of charge doping and biaxial strains on the transition temperature of charge density wave (CDW) transition in TiSe2. We find soft phonon modes at the M and L points in the Brillouin zone of TiSe2, and a 0.043 eV Fermi-Dirac smearing width can suppress these soft modes. In this way, the transition temperature of CDW is quantitatively represented by the smearing width. After doping with electrons or holes, we find that the critical smearing widths to eliminate the CDW transition both decrease, indicating the same suppression effect on the CDW transition of electron doping and hole doping. Comparatively, only compressive biaxial strains can lower down the transition temperature of CDW transition in TiSe2, while stretching strains enlarges the transition temperature.