BAND STRUCTURE, PHYSICAL PROPERTIES, AND STABILITY OF TIO BY AUGMENTED-PLANE-WAVE VIRTUAL-CRYSTAL APPROXIMATION

The augmented-plane-wave virtual-crystal approximation is used to compute band structures and densities of states of the titanium monoxide system as a function of vacancy concentration and composition. TiO is a nonstoichiometric, cubic refractory compound with a 15% intrinsic vacancy concentration on both sublattices. The effective-mass approximation and an experimental value for the electron relaxation time are used to estimate several transport properties. The theoretical values are compared with experiment and used to examine the validity of our one-electron, muffin-tin-potential model of a nonstoichiometric compound. As it stands, this model does not treat the potential between the muffin-tin spheres accurately. It gives a physically valid description for most transport properties, but not for cohesion. Nonetheless, if the conduction-band edge does not vary appreciably with composition or total vacancy concentration, the average electronic energy is a minimum at the observed vacancy concentration. © 1969 The American Physical Society.