Electronic energy gaps and optical properties of LaMnO3

► Understanding LaMnO3 is crucial to explore manganites for spintronics. ► We investigate LaMnO3 through DFT calculations with a new exchange potential. ► Calculated electronic and optical results are better than those with GGA and LDA. ► Calculated results are in excellent agreement with experiment. ► These lead to a satisfactory DFT understanding of LaMnO3 without tuning parameters.