Strongly Correlated Effect in TiS₂

The thermoelectric compound TiS₂ is studied by using the full-potential linearized augmented plane-wave method on the density functional theory with the generalized gradient approximation (GGA) as well as the on-site Coulomb interaction correction (+U). The Seebeck coefficient of TiS₂ is calculated based on the electronic structure obtained within the GGA under the consideration of the on-site Coulomb interaction. The calculated Seebeck coefficient at 300K shows that Coulomb interaction U in the range of 4.97--5.42eV is important to reproduce the experimental data. The obtained energy gap E_g around 0.05eV indicates that TiS₂ is an indirect narrow-gap semiconductor.