Accuracy of quantum chemical methods for large noncovalent complexes

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-D3H4. The test complexes are the octadecane dimer, the guanine trimer, the circumcoronene···adenine dimer, the coronene dimer, the guanine-cytosine dimer, the circumcoronene···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 25%). 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. © 2013 American Chemical Society.

Duke Scholars

Author Tomasz Janowski