The meta-GGA functional: Thermochemistry with a kinetic energy density dependent exchange-correlation functional

The meta-GGA functional recently proposed by Perdew [Phys. Rev. Lett. 82, 2544 (1999)] goes beyond the generalized gradient approximations (GGAs) since it employs the noninteracting kinetic energy density in addition to the local density and the gradient of the local density. In this paper, we focus on thermochemistry and present an extensive assessment of the meta-GGA functional. We find that for atomization energies meta-GGA is as accurate as the computationally more involved Perdew-Burke-Ernzerhof (PBE) hybrid scheme. However, the geometries and frequencies obtained with meta-GGA are worse than those obtained with PBE or PBE hybrid. We give a detailed analysis of our results and propose explanations for the observed differences between PBE, PBE hybrid, and meta-GGA. Furthermore, we address the question whether the parameters in the meta-GGA functional are optimal for our benchmark set. (C) 2000 American Institute of Physics. [S0021-9606(00)31304-6].