First principles calculations of electronic structures for orthorhombic and monoclinic Cu₄SnS₄

Electronic structures of orthorhombic and monoclinic Cu₄SnS₄, which exhibit a first-order phase transition at 232 K, are demonstrated based on the generalized gradient approximation (GGA) of the density functional theory (DFT). The calculated band gap was 0.39 eV for orthorhombic phase, while that was not obtained for monoclinic one. These calculated results confirm monoclinic phase has smaller activation energy (E_a) than orthorhombic phase.