Performance of a nonempirical exchange functional from density matrix expansion: comparative study with different correlations

Abstract

Recently, Tao and Mo proposed a meta-generalized gradient approximation for the exchange–correlation energy with remarkable accuracy for molecules, solids, and surfaces. To better understand this functional, in this work, we make a comparative study of the TM and TMTPSS functionals, the latter of which is a combination of the TM exchange with the original TPSS correlation functional, on atoms, molecules, and hydrogen-bonded complexes by the use of eight well-known databases. Our calculations show that, while the TMTPSS functional achieves better accuracy for atomization energies or enthalpies of formation, harmonic vibrational frequencies, and atomic excitation energies than the TM functional, it is less accurate for proton affinities, molecular bond lengths, and in particular hydrogen-bonded complexes.