Investigate the Bi2Se3 Crystal, which is a Three-Dimensional Topological Insulator.

Topological insulators are materials that in bulk mode have band gap such as an ordinary insulator but can protect the conduction mode at the edge or surface, i.e. apart from a simple and insulated metal. These materials are insulator in their bulk modes but are metal at the surface. Topological insulators are developed in two and three dimensions. Recently, compounds of the Bi2Se3 have attracted a huge attention because of existence of a Dirac cone in their surface state, having a suitable bandgap (0.3 eV), and easy santhesis. In this research, we investigate the properties of this material using density functional theory. The main focus is on bulk calculations and surface properties. The band structure of this material is studied in bulk mode without any consideration of spin - orbit interaction. Then a surface of this material is considered and its band structure and density of states are studied. The results show that the surface of this material has a Dirac cone. [ABSTRACT FROM AUTHOR]