Electronic band structure and photoemission states of Bi1.96Mg0.04Se3

Abstract

We present theoretical band structure calculations and ultraviolet electron photoemission spectroscopy of a topological insulator Bi1.96Mg0.04Se3. Our calculations were based on the first-principles density functional theory with general gradient approximation using Wien2k package with the spin-orbit interaction included by a second-variation method. The R3̄m crystal structure was optimized. In consequence, 4% decrease of volume and 3% decrease of ratio c/a was obtained. This modified structure was multiplied three times in a and b direction in order to place proper amount of Mg. Final crystal structure P3m1 with 135 atoms was used for the calculations. As a result metallic band structure was obtained with conduction band extended from -5.6 eV up to 0.16 eV. It composes mostly from Se p states. Comparison of total DOS with ultraviolet photoemission spectrum shows similar features.