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+USIC scheme by comparing the exact exchange (EXX) hole with the LDA exchange hole. The LDA+USIC method yields good band-gap energies Eg and dielectric constants ε(ω≈ 0) of Si, Ge, GaAs, and ZnSe. We also show that LDA consistently underestimates the Γ-point effective electron mc and light-hole mlh 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 dand f -orbitals.