Improved LDA-1/2 method for band structure calculations in covalent semiconductors

Abstract

The LDA-1/2 method for self-energy correction is a powerful tool for calculating accurate band structures of semiconductors, while keeping the computational load as low as standard LDA. Nevertheless, controversies remain regarding the choice between (1/2)e and (1/4)e charge stripping from the atoms in group IV semiconductors, the incorrect direct band gap predicted for Ge, and inaccurate band structures for III–V semiconductors. Here we propose an improved method named shell-LDA-1/2 (shLDA-1/2 for short), which is based on a shell-like trimming function for the self-energy potential. With the new approach, we obtained improved band structures for group IV, and for III–V and II–VI compound semiconductors. In particular, with shLDA-1/2 we reproduced the complete band structures of Ge in good agreement with experimental data. Moreover, we have defined clear rules for choosing the amount of charge that ought to be stripped in covalent semiconductors, i.e., (1/2)e or (1/4)e.