Efficient Implementation of the Random Phase Approximation with Domain-Based Local Pair Natural Orbitals.

We present an efficient implementation of the direct random phase approximation (RPA) for molecular systems within the domain-based local pair natural orbital (DLPNO) framework. With recommended loose, normal, and tight parameter settings, DLPNO-RPA achieves approximately 99.7-99.95% accuracy in the total correlation energy compared to a canonical implementation, enabling highly accurate reaction energies and potential energy surfaces to be computed while substantially reducing computational costs. As an application, we demonstrate the capability of DLPNO-RPA to efficiently calculate basis set-converged binding energies for a set of large molecules, with results showing excellent agreement with high-level reference data from both coupled cluster and diffusion Monte Carlo. This development paves the way for the routine use of RPA-based methods in molecular quantum chemistry.