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Abstract: We model a Kohn-Sham potential with a discontinuity at integer particlenumbers derived from the GLLB approximation of Gritsenko et al. We evaluate theKohn-Sham gap and the discontinuity to obtain the quasiparticle gap. Thisallows us to compare the Kohn-Sham gaps to those obtained by accurate many-bodyperturbation theory based optimized potential methods. In addition, theresulting quasiparticle band gap is compared to experimental gaps. In the GLLBmodel potential, the exchange-correlation hole is modeled using a GGA energydensity and the response of the hole to density variations is evaluated byusing the common-denominator approximation and homogeneous electron gas basedassumptions. In our modification, we have chosen the PBEsol potential as theGGA to model the exchange hole, and add a consistent correlation potential. Themethod is implemented in the GPAW code, which allows efficient parallelizationto study large systems. A fair agreement for Kohn-Sham and the quasiparticleband gaps with semiconductors and other band gap materials is obtained with apotential which is as fast as GGA to calculate.



Author: M. Kuisma, J. Ojanen, J. Enkovaara, T.T. Rantala

Source: https://arxiv.org/







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