Some Observations on the Performance of the Most Recent Exchange-Correlation Functionals for the Large and Chemically Diverse GMTKN55 Benchmark

TL;DR

This study evaluates the performance of recent exchange-correlation functionals on the GMTKN55 benchmark, revealing the importance of dispersion corrections, the effectiveness of combinatorial development, and identifying top-performing functionals like {}B97M(2).

Contribution

It provides a comprehensive assessment of the latest DFT functionals on a diverse benchmark, highlighting development strategies and the impact of dispersion models.

Findings

{}B97M(2) is currently the best DFT functional.

revDSD-D4 functionals achieve similar performance with fewer parameters.

D4 dispersion model outperforms D3BJ and NL models.

Abstract

Benchmarks that span a broad swath of chemical space, such as GMTKN55, are very useful for assessing progress in the quest for more universal DFT functionals. We find that the WTMAD2 metrics for a great number of functionals show a clear "Jacob's Ladder hierarchy"; that the "combinatorial" development strategy of Head-Gordon and coworkers generates "best on rung" performers; that the quality of the nonlocal dispersion correction becomes more important as functionals become more accurate for nondispersion properties; that fitting against small, unrepresentative benchmark sets leads to underperforming functionals; and that {\omega}B97M(2) is currently the best DFT functional of any kind, but that revDSD-D4 functionals are able to reach similar performance using fewer parameters, and that revDOD-D4 in addition permits reduced-scaling algorithms. If one seeks a range-separated hybrid (RSH) GGA that also performs well for optical excitation energies, CAM-QTP-01 may be a viable option. The D4 dispersion model, with its partial charge dependence, appears to be clearly superior to D3BJ and even possibly NL. Should one require a double hybrid without dispersion model, noDispSD-SCAN is a viable option. Performance for the MOBH35 transition metal benchmark is different: the best double hybrids are competitive but not superior to {\omega}B97M-V, which offers the best performance compromise for mixed main group-transition metal problems.