As4Se4 crystal versus As4Se4 molecule: A plane wave DFT study of the geometric and electronic structure

Abstract

Сhalcogenide crystals reveal a wide range of changes in chemical and physical properties under band gap light illumination. A majority of these properties are determined by the electronic structure. However, to date there are only a few theoretical articles on the electronic structure of the As4Se4 molecule and only two on the As4Se4 crystal. We have studied, for the first time, the geometric and electronic structure of the As4Se4 crystal versus the As4Se4 molecule in the framework of a periodic model by the DFT method within the same approximations. Equilibrium bond lengths and bond angles were calculated together with charge density differences, Mulliken, Lowdin and Bader charges, and also Mulliken overlap populations, and were compared for the crystal and the molecule. A character of chemical bonding in the As4Se4 crystal versus the As4Se4 molecule was analyzed. The bandstructure DFT calculations were carried out and demonstrated that the As4Se4 crystal is an indirect-gap semiconductor.

Keywords

• chalcogenides
• geometric and electronic structure
• chemical bonding
• As4Se4
• molecule
• molecular crystal