Density Functional Treatment of an Exactly Solvable Semiconductor Model - Comment

Since the deduction of a discontinuity in the density functional exchange-correlation potential v sub (xc) across the energy gap [1,2], Godby et al. [3] resolved the so-called energy gap problem by demonstrating that within the random phase approximation for diamond, Si, GaAs, and AlAs the deviation of the energy gap in the local density approximation (LDA) from the true gap is due in large part (over 80% in all cases) to the discontinuity.