A quantum-mechanical model of dilatation dipoles in topochemical synthesis of silicon carbide from silicon

The interaction between a silicon vacancy and a carbon atom formed in silicon during the topochemical synthesis of silicon carbide from silicon has been calculated using the density functional theory method. It has been shown that the silicon vacancy and the carbon atom are attracted to each other, and the strongest attraction is observed in the $\langle$111$\rangle$ direction. It has been established that there a qualitative agreement between the quantum-mechanical theory and the theory based on the Green’s function method for point defects. It has been concluded that the silicon vacancy and the carbon atom form a bound state in silicon. The effective stiffness coefficient of this coupling in the $\langle$111$\rangle$ direction has been estimated to be 5 eV/$\mathring{\mathrm{A}}^{2}$.