Improved electronic structure and optical properties of sp-hybridized semiconductors using LDA+USIC

We propose the local density approximation (LDA) plus an on-site Coulomb self-interaction-like correction (SIC) potential for describing sp-hybridized bonds in semiconductors and insulators. We motivate the present LDA+U-SIC scheme by comparing the exact exchange (EXX) hole with the LDA exchange hole. The LDA+U-SIC method yields good band-gap energies E-g and dielectric constants (omega approximate to 0) of Si, Ge, GaAs, and ZnSe. We also show that LDA consistently underestimates the Gamma-point effective electron m, and light-hole M-lh masses, and the underlying reason for this is a too strong light-hole-electron coupling within LDA. The advantages of the LDA+USIC approach are a computational time of the same order as the ordinary LDA, the orbital dependent LDA+USIC exchange-correlation interaction is asymmetric analogously to the EXX potential, and the method can be used for materials and compounds involving localized d- and f-orbitals.