The band gap problem: the accuracy of the Wien2k code confronted

This paper is a continuation of our detailed study [Phys. Rev. B 86, 195106 (2012)] of the performance of the recently proposed modifiedBecke-Johnson potential (mBJLDA) within the known Wien2k code. From the 41 semiconductors that we have considered in our previouspaper to compute the band gap value, we selected 27 for which we found low temperature experimental data in order to pinpoint the relativesituation of the newly proposed Wien2k(mBJLDA) method as compared to other methods in the literature. We found that the GWA gives themost accurate predictions. The Wien2k (mBJLDA) code is slightly less precise, in general. The Hybrid functionals are less accurate, on theoverall. The GWA is definitely the most precise existing method nowadays. In 88% of the semiconductors considered the error was less than10%. Both, the GWA and the mBJLDA potential, reproduce the band gap of 15 of the 27 semiconductors considered with a 5% error or less.

An extra factor to be taken into account is the computational cost. If one would seek for precision without taking this factor into account,the GWA is the method to use. If one would prefer to sacrifice a little the precision obtained against the savings in computational cost, theempirical mBJLDA potential seems to be the appropriate method.

We include a graph that compares directly the performance of the bestthree methods, according to our analysis, for each of the 27 semiconductors studied. The situation is encouraging but the problem is not yeta closed issue.

Keywords:Band gap problem; Wien2k; mBJLDA potential; hybrid functionals; GW approximation.


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http://rmf.smf.mx/pdf/rmf/59/5/59_5_453.pdf