DFT-SAPT Intermolecular Interaction Energies Employing Exact-Exchange Kohn-Sham Response Methods.

Intermolecular interaction energies have been calculated by symmetry-adapted perturbation theory based on density functional theory monomer properties (DFT-SAPT) employing response functions from time-dependent exact-exchange (TDEXX) kernels. Combined with a new asymptotic correction scheme for the exchange-correlation (xc) potentials of the monomers, which is similar in its performance to standard asymptotic correction methods, it is shown that this DFT-SAPT[TDEXX] method delivers highly accurate intermolecular interaction energies for the S22, S66, and IonHB benchmark databases by Hobza et al. A corresponding DFT-SAPT approach employing the adiabatic TDEXX kernel in the response calculations has also been tested. This DFT-SAPT[ATDEXX] method performs almost as well as DFT-SAPT[TDEXX] for dispersion-dominated dimer systems but less accurately for hydrogen-bonded dimers. Compared to this, DFT-SAPT[TDEXX] yields a balanced description of the interaction energies for various interaction-type motifs, similar to the standard DFT-SAPT method that utilizes the ALDA xc kernel to compute the response functions.