DFT based Symmetry-Adapted Perturbation Theory Calculations for Large Dimers

KRZYSZTOF SZALEWICZ; JAVIER GARCIA

Park City

Workshop; The Utah Workshop on Quantum Methods in Molecular and Solid-State Theory; 2019

University of Utah

Symmetry Adapted Perturbation Theory (SAPT) \cite{SAPT} methods provide intermolecular interaction energies naturally by splitting a molecular complex into its isolated monomers and treating their interaction perturbatively. One of the benefits of this approach is that it allows to analyze the intermolecular interaction energy by its individual electrostatic, exchange, induction, and dispersion components.One of such approaches, SAPT(DFT), is based on the DFT description of the monomers for first order terms, and the frequency-dependent density susceptibilities (FDDSs) computed with time-dependent DFT for second order terms. It has proven to produce very accurate interaction energies at a reasonable computational cost, with the most expensive parts usually being the calculation of the FDDSs and the exchange-dispersion energy.With increasing availability of computational power, in terms of disk storage, memory capacity, and raw CPU performance, SAPT(DFT) calculations of interaction energies for large dimers can be achieved, provided that algorithms are designed in a way that takes advantage of these new features efficiently.We discuss our progress in the design of such algorithms, including major gains in terms of disk space and memory required, and time required, allowing us to compute SAPT(DFT) interaction energies for large systems, such as the Buckycatcher fullerene complex.