First-principles study of bulk and (001) surface of TiC
(1. Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education,
Shandong University, Ji’nan 250061, China;
2. School of Mechanical and Electronic Engineering, Shandong University at Weihai, Weihai 264209, China)
Shandong University, Ji’nan 250061, China;
2. School of Mechanical and Electronic Engineering, Shandong University at Weihai, Weihai 264209, China)
Abstract: The structural and electronic properties of bulk and (001) plane of TiC were investigated by the first-principles total-energy pseudopotential method based on density functional theory. The calculated bulk properties indicate that bonding nature in TiC is a combination of ionicity, covalency and metallicity, in which the Ti—C covalent bonding is the predominate one. The calculated results of structural relaxation and surface energy for TiC(001) slab indicate that slab with 7 layers shows bulk-like characteristic interiors, and the changes of slab occur on the outmost three layers, which shows that the relaxation only influences the top three layers. Meanwhile, the strong Ti—C covalent bonding can be found in the distribution of charge density on the (110) and (001) planes. Ti—C covalent bonding is enhanced by the charge depletion and accumulation in the vacuum and the interlayer region between top two atomic layers.
Key words: first-principles; TiC; charge transfer; structural relaxation