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MM: Fachverband Metall- und Materialphysik

MM 57: Methods in Computational Materials Modelling (methodological aspects, numerics)

MM 57.2: Vortrag

Donnerstag, 15. März 2018, 12:00–12:15, TC 006

Assessment of the GLLB-SC potential for solid-state properties and attempts of improvement — •Fabien Tran, Sohaib Ehsan, and Peter Blaha — Vienna University of Technology, Vienna, Austria

Based on the work of Gritsenko et al. (GLLB) [Phys. Rev. A 51, 1944 (1995)], the method of Kuisma et al. [Phys. Rev. B 82, 115106 (2010)] to calculate the band gap in solids was shown to be much more accurate than the common methods of the local density approximation (LDA) and generalized gradient approximation (GGA). The main feature of the GLLB-SC potential (SC stands for solid and correlation) is to lead to a nonzero derivative discontinuity that can be conveniently calculated and then added to the Kohn-Sham band gap for a comparison with the experimental band gap. In this work, a thorough comparison of GLLB-SC with other methods, e.g., the modified Becke-Johnson (mBJ) potential [F. Tran and P. Blaha, Phys. Rev. Lett. 102, 226401 (2009)], for electronic, magnetic, and density-related properties is presented. It is shown that for the band gap, GLLB-SC does not perform as well as mBJ for systems with a small band gap and strongly correlated systems, but is on average of similar accuracy as hybrid functionals. The results on itinerant metals indicate that GLLB-SC overestimates significantly the magnetic moment (much more than mBJ does), but leads to excellent results for the electric field gradient, for which mBJ is in general not recommended. In the aim of improving the results with the idea of GLLB, variants of the GLLB-SC potential are also tested.