Abstract
We evaluate the performance of the most widely used wave function, density functional theory, and semiempirical methods for the description of noncovalent interactions in a set of larger, mostly dispersion-stabilized noncovalent complexes (the L7 data set). The methods tested include MP2, MP3, SCS-MP2, SCS(MI)-MP2, MP2.5, MP2.X, MP2C, DFT-D, DFT-D3 (B3-LYP-D3, B-LYP-D3, TPSS-D3, PW6B95-D3, M06-2X-D3), and M06-2X, and semiempirical methods augmented with dispersion and hydrogen bonding corrections: SCC-DFTB-D, PM6-D, PM6-DH2, and PM6-3H4.
The test complexes are the octadecane dimer, the guanine trimer, the circumcoronene center dot center dot center dot adenine dimer, the coronene dimer, the guanine-cytosine dimer, the circumcoronene center dot center dot center dot guanine-cytosine dimer, and an amyloid fragment trimer containing phenylalanine residues. The best performing method is MP2.5 with relative root-mean-square deviation (rRMSD) of 4%.
It can thus be recommended as an alternative to the CCSD(T)/CBS (alternatively QCISD(T)/CBS) benchmark for molecular systems which exceed current computational capacity. The second best non-DFT method is MP2C with rRMSD of 8%.
A method with the most favorable "accuracy/cost" ratio belongs to the DFT family: BLYP-D3, with an rRMSD of 8%. Semiempirical methods deliver less accurate results (the rRMSD exceeds 2596).
Nevertheless, their absolute errors are close to some much more expensive methods, such as M06-2X, MP2, or SCS(MI)-MP2, and thus their price/performance ratio is excellent.