A local-density approximation for the exchange energy functional for excited states: The band-gap problem

We present excited-state density functional theory (DFT) to calculate band gap for semiconductors and insulators. For the excited-state exchange-correlation functional, we use a simple local-density approximation (LDA) like functional and it gives the result which is very close to experimental results. The linear muffin-tin potential is used to solve the self-consistent Kohn–Sham equation.