Electronic structure and energies of interatomic bonds in the TiSi2 compound with a C49 crystal structure

Abstract

Full-electron calculations of the electronic structure of the TiSi2 compound in the structural modification C49 are performed using the augmented-plane-wave method. The total energy, the electronic band structure, and the density of states are calculated for an extended translational unit cell Ti4Si8, which is formed during the growth of a silicon nanowire on a p-Si substrate. Calculations are also carried out for two orthorhombic unit cells of the nonstoichiometric compositions Ti3Si9 and Ti5Si7. The energies of the interatomic bonds are determined to be ESi-Si = 1.8 eV, ETi-Ti = 2.29 eV, and ETi-Si = 4.47 eV. The dependence of the total energy of the unit cell Etot(V) on the unit cell volume V is obtained by optimizing the unit cell volume. The bulk modulus B0 = 132 GPa is determined from the Murnaghan equation of state for solids and the dependence Etot (V). This value of the bulk modulus is used to estimate the activation energy for interstitial diffusion of silicon atoms Qi(Si) ≈ 0.8 eV.