Multi-reference calculations are necessary for accurate descriptions of electronic structure for a large variety of molecules. However, these calculations suffer from exponentially scaling computational cost. Localized Active Space Self Consistent Field (LASSCF) calculations can be used to reduce this cost in systems with multiple fragments with a strong correlation within them but only weak correlation between them. LASSCF treats a system’s active orbitals by localizing them over several fragments that are treated as unentangled active sub-spaces. Here we investigate Cu2O22+-based systems, which are known to have complex electronic structures and are biologically relevant. Cu2O22+ species are found in natural metalloenzymes that oxidize various substrates using molecular oxygen. The most accurate theories are often prohibitively expensive for systems even as small as Cu2O22+. We investigate the accuracy of LASSCF for this system. The energy differences between the bis-µ-oxo and peroxo structures are calculated using LASSCF and are compared to the corresponding CASSCF energies. Various active spaces are chosen for this comparison and a variety of fragmentation schemes are tested for LASSCF.

Localized active space self-consistent field treatment of Cu2O22+: Accuracy and affordability

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.