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

TL;DR

This study evaluates the TMTPSS exchange-correlation functional, combining TM exchange with TPSS correlation, demonstrating its high accuracy in predicting molecular properties and outperforming some existing functionals.

Contribution

The paper introduces and systematically assesses the TMTPSS functional, a nonempirical exchange-correlation functional based on the density matrix expansion, for various molecular properties.

Findings

TMTPSS is highly accurate for enthalpies of formation.

It outperforms TM functional in some molecular property predictions.

TMTPSS is the most accurate nonempirical semilocal DFT for certain vibrational frequencies.

Abstract

Recently, Tao and Mo proposed an accurate meta-generalized gradient approximation for the exchange-correlation energy. The exchange part is derived from the density matrix expansion, while the correlation part is obtained by improving the TPSS correlation in the low-density limit. To better understand this exchange functional, in this work, we combine the TM exchange with the original TPSS correlation, which we call TMTPSS, and make a systematic assessment on molecular properties. The test sets include the 223 G3/99 enthalpies of formation, 58 electron affinities, 8 proton affinities, 96 bond lengths, 82 harmonic frequencies, and 10 hydrogen-bonded molecular complexes. Our calculations show that the TMTPSS functional is competitive with or even more accurate than TM functional for some properties. In particular, it is the most accurate nonempirical semilocal DFT for the enthalpies of formation and harmonic vibrational frequencies, suggesting the robustness of TM exchange.