Exciton condensation temperature in a transition metal dichacogenide 1T-TiSe2.

We revisit the question of the transition metal dichacogenide TiSe2 charge density wave (CDW) state being an excitonic insulator. The BCS-like CDW gap equation with the inter and intra-band Coulomb interactions was employed to calculate the transition temperature as a function of the band gap. Realistic dispersions for one hole band centered at Γ and three electron bands at M points were considered to model the 1T-TiSe2. We discuss possibility of the 1T-TiSe2 CDW state originating from exciton condensation through the calculated phase diagram.