Communication: Surface stability and topological surface states of cleaved Bi2Se3: First-principles studies

Through systematic first principles calculations within the nonlocal van der Waals functional, we investigated the structure stability and topological surface state properties of various surface cleaves in the topological insulator Bi2Se3 Our results reveal that under Bi-rich conditions, the Bi bilayer-covered surface and the Se-terminated surface with a Bi bilayer under the first quintuple layer are even more stable than the generic Bi2Se3. The surface state bands are changed by different surface terminations, causing the formation of new Dirac states. We may distinguish various surfaces by using scanning tunneling microscopy experimentally.