Real space molecular orbital view of 2D materials
Fang-Cheng Chou1,2*
1Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
2National Synchrotron Radiation Research Center, Hsinchu, Taiwan
* presenting author:Fang Cheng Chou,
2D layered materials are often used to describe the physically cleavable compounds with intra-layer closely packed atoms of assumed van der Waals gap between layers. Band calculations from crystal symmetry of atoms without considering the actual coordination and valence electron availability at the molecular level could miss the existence of other types of chemical bond beyond the picture of covalent σ bond. I will use several typical layered compounds, including Curie-Weiss metal NaxCoO2, controversial semimetal-semiconductor TiSe2, topological insulator Bi2Se3, topological crystalline insulator Pb1-xSnxSe, and a few recently developed Dirac and Weyl semimetals as examples, to demonstrate the effectiveness of applying the molecular orbital concept to describe 2D materials with predictable physical properties.

Keywords: 2D materials, molecular orbital, topological order