QuantumMechanical Calculation of Noncovalent Interactions:A Large-Scale Evaluation of PMx DFT and SAPT Approaches

摘要

Quantum mechanical (QM) calculations of noncovalent interactions are uniquely useful as tools to test and improve molecular mechanics force fields and to model the forces involved in biomolecular binding and folding. Because the more computationally tractable QM methods necessarily include approximations, which risk degrading accuracy, it is essential to evaluate such methods by comparison with high-level reference calculations. Here, we use the extensive Benchmark Energy and Geometry Database (BEGDB) of CCSD(T)/CBS reference results to evaluate the accuracy and speed of widely used QM methods for over 1200 chemically varied gas-phase dimers. In particular, we study the semiempirical PM6 and PM7 methods; density functional theory (DFT) approaches B3LYP, B97-D, M062X, and ωB97X-D; and symmetry-adapted perturbation theory (SAPT) approach. For the PM6 and DFT methods, we also examine the effects of post hoc corrections for hydrogen bonding (PM6-DH+, PM6-DH2), halogen atoms (PM6-DH2X), and dispersion (DFT-D3 with zero and Becke–Johnson damping). Several orders of theSAPT expansion are also compared, ranging from SAPT0 up to SAPT2+3,where computationally feasible. We find that all DFT methods withdispersion corrections, as well as SAPT at orders above SAPT2, consistentlyprovide dimer interaction energies within 1.0 kcal/mol RMSE acrossall systems. We also show that a linear scaling of the perturbativeenergy terms provided by the fast SAPT0 method yields similar highaccuracy, at particularly low computational cost. The energies ofall the dimer systems from the various QM approaches are includedin the Supporting Information, as are the full SAPT2+(3) energy decompositionfor a subset of over 1000 systems. The latter can be used to guidethe parametrization of molecular mechanics force fields on a term-by-termbasis.