Perdew-Kurth-Zupan-Blaha functional

Tao-Perdew-Staroverov-Scuseria) exchange-correlation functional, on the other hand, is a non-empirical version that represents a further development of the PKZB (Perdew-Kurth-Zupan-Blaha) functional, and can be considered as the next improvement over the PBE functional. ... 

PKZB Perdew, Kurth, Zupan, and Blaha s MGGA exchange-correlation functional developed primarily for solids. Perdew, J. P., Kurth, S., Zupan, A., and Blaha, P. 1999. Phys. Rev. Lett., 82, 2544. 

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