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At the generalized gradient (GGA) level of approximation, one faces the dilemma of choosing between good results for atoms and molecules or for solids. A recent PBEsol study [1] suggests that better bond lengths and lattice constants can be found when the exchange functional recovers the secondorder gradient expansion over a wide range of densities. PBEsol diminishes the gradient dependence of the PBEGGA [2], and consequently loses accuracy for the atomization energies of molecules. Better lattice constants and atomization energies are found only at the metaGGA level of approximations. The TPSS 2003 metaGGA [3], however, is not accurate enough for the lattice constants. This main deficiency of the TPSS semilocal functional is rectified by a better metaGGA. With some change in the original TPSS functional suggested by the PBEsol insight, while retaining the paradigms of quantum chemistry (one –and two electron atoms) and solid state physics (slowly varying densities), our revised TPSS metaGGA [4] yields very good lattice constants, surface energies, and atomization energies. This metaGGA can be used as an ingredient of higherlevel functionals like hyperGGA`s and longrange corrected hybrids. On the other hand, for atoms and molecules, a strongly diminished PBE works well when combined with a scaleddown selfinteraction correction [5] (although perhaps not significantly better than LSDA). This shows that the undiminished gradient dependence of PBE and related functionals works somewhat like a scaleddown selfinteraction correction to LSDA. [1] J.P. Perdew, A. Ruzsinszky, G.I. Csonka, L.A. Constantin, X. Zhou, O.A. Vydrov, G.E. Scuseria, and K. Burke, Phys. Rev. Lett. 100, 136406 (2008). [2] J. P. Perdew, K. Burke, and M. Ernzerhof, Phys. Rev. Lett. 77, 3865 (1996) [3] J. Tao, J.P. Perdew, V.N. Staroverov, and G.E. Scuseria, Phys. Rev. Lett. 91, 146401 (2003). [4] J.P. Perdew, A. Ruzsinszky, G.I. Csonka, L.A. Constantin, and J. Sun, submitted. [5] O. A. Vydrov, G. E. Scuseria, A. Ruzsinszky, J. P. Perdew, and G. I. Csonka, J. Chem.Phys. 124, 094108 (2006).
Dr. Ruzsinszky will visit Los Alamos from 5/10 to 5/15 (before 10:am). If you would like to talk with her, please contact Dr. Jianmin Tao at jtao@lanl.gov or 6676840.
