A density-functional based tight-binding approach to III–V semiconductor clusters

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Abstract
We determine here the Hamiltonian and overlap matrix elements necessary in a non-orthogonal two-centre tight-binding (TB) scheme for gallium, aluminium, arsenic, gallium arsenide and aluminium arsenide using a local density-functional method. The repulsive energy required by such methods is described by radial short-range repulsive pair contributions. These are determined with respect to self-consistent cohesive energy calculations performed on diatomic molecules and bulk crystalline forms. Without inclusion of any parameters, we show that the method can be applied successfully to simulations of small homo- and hetero-nuclear clusters giving an accuracy comparable to ab initio calculations. In addition, we prove the transferability of the scheme to the crystalline modifications of As, Al, Ga, GaAs and AlAs by determining the equilibrium structural, vibrational and electronic band-structure properties.