A Comparative Analysis of Symmetry-Adapted Perturbation Theory

Noncovalent interaction are prevalent in chemical systems including protein folding, organic crystals, nucleic acids, and the formation of materials. These interactions are quantitatively and qualitatively studied by employing computationally expensive wavefunction-based quantum chemical methods. One method in particular, Symmetry-Adapted Perturbation Theory(SAPT), allows the interaction energy to be computed along with the electrostatic, exchange, induction, and dispersion energies. Here, various levels of SAPT were tested using the S22, HSG, HBC6, and NBC10 databases in order to find a lower level of SAPT that produced accurate results at a low computational cost. Four levels of SAPT and 10 Basis sets were used in this study with the best overall test pairs being SAPT2+/aDZ and SAPT2+(3)/aDZ. However, since both SAPT2+ and SAPT2+(3) are higher levels of theory, they are quite costly. For both high accuracy and low computational expense, the SAPT0/jaDZ test pair is an exceptional match. SAPT0/jaDZ produced a mean unsigned error of less than 0.5 kcal mol^-1 at roughly one-half and one-quarter the computational times for SAPT2+/aDZ and SAPT2+(3)/aDZ, respectively.