All-electron mixed-basis calculation of structurally optimized titanium nitride clusters

Ab initio total energy calculations based on the local density approximation (LDA) and the adiabatic approximation has attracted considerable attention as a conceptually new method. It is capable of describing dynamically the stability and reactivity of clusters, surfaces and bulk materials at finite temperatures, in principle, without using any adjustable parameters. Consequently, Ohno et al. have developed the all-electron mixed-basis approach which is applicable to the molecular dynamics of objects in any atomic environment. Titanium Nitride has unique features, such as self-lubricity, high wear resistance, high melting point, and high hardness, and the application to artificial bone and cutting tools, among others, is expected. We calculated optimized structures of titanium nitride micro clusters and compared these with silicon nitride which is tetravalent also. Both TiN₂ and SiN₂ clusters form isosceles triangles. The Ti-N bondlengths in TiN and TiN₂ are much shorter than in the bulk.