We explore a separable resolution-of-the-identity (RI) formalism built on quadratures over limited sets of real-space points designed for all-electron calculations. Our implementation preserves, in particular, the use of common atomic orbitals and their related auxiliary basis sets. The setup of the present density fitting scheme, i.e., the calculation of the system specific quadrature weights, scales cubically with respect to the system size. Extensive accuracy tests are presented for the Fock exchange and MP2 correlation energies. We finally demonstrate random phase approximation (RPA) correlation energy calculations with a scaling that is cubic in terms of operations, quadratic in memory, with a small crossover with respect to our standard RI-RPA implementation.
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We will distinguish strong localization properties that are independent of the system and weak localization that depends on the system characteristics (e.g., its dimensionality, size, electronic HOMO-LUMO gap, etc.).
All calculations were performed on 2 nodes of 2 × 16 cores of Intel Xeon Gold 6130 CPU @ 2.10 GHz, with Intel Omni-Path Interconnect, except for the RI-V RPA correlation energy of the octapeptide angiotensin II molecule where 4 half filled nodes were used in order to circumvent memory issues.
