Semi-empirical or non-empirical double-hybrid density functionals: which are more robust?

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Density Functional Theory (DFT)

Background:

• The rapid development of non-empirical double-hybrid density functionals (DHDFs) has outpaced comparative assessments against semi-empirical DHDFs.
• A comprehensive, side-by-side evaluation of non-empirical and semi-empirical DHDFs is lacking, hindering informed method selection for researchers.

Purpose of the Study:

• To provide a thorough and fair comparison between non-empirical and semi-empirical DHDFs.
• To benchmark the performance of 115 dispersion-corrected and -uncorrected DHDF variations on the GMTKN55 database.

Main Methods:

• Systematic assessment of 31 selected DHDFs (19 non-empirical, 12 semi-empirical) using the GMTKN55 benchmark database.
• Evaluation covered general main-group thermochemistry, kinetics, and noncovalent interactions.
• Inclusion of dispersion-corrected and -uncorrected methods, as well as comparisons with MP2 and SCS-MP2.

Main Results:

• Semi-empirical DHDFs demonstrate superior robustness, reliability, and accuracy compared to non-empirical DHDFs.
• Several non-empirical methods were outperformed by simpler hybrid or MP2-based approaches.
• Only SOS0-PBE0-2-D3(BJ) was recommended among non-empirical DHDFs, but it was still surpassed by six semi-empirical DHDFs.

Conclusions:

• The study's findings challenge current trends favoring non-empirical DHDF development.
• Novel strategies are needed to surpass the performance of the best currently available semi-empirical DHDFs.
• Recommended semi-empirical DHDFs include ωB97X-2-D3(BJ), DSD-BLYP-D3(BJ), DSD-PBEP86-D3(BJ), B2NC-PLYP-D3(BJ), and B2GPPLYP-D3(BJ).