Local Orbitals in Quantum Chemistry

Abstract

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Modelling Heterogeneous Catalysis using Quantum Computers: An academic and industry perspective

“…Spatially localized MOs can be constructed to provide a better understanding of chemical bonding and photochemistry of the system. 245 Such localized MOs (LMOs) are particularly important in local correlation treatments within post-HF methods. These LMOs serve as excellent starting orbitals for multi-configuration calculations, such as state-averaged complete active space self-consistent field (SA-CASSCF), 246,247 as well as for quantum calculations like state-averaged orbitaloptimzied variational quantum eigensolver (SA-OO-VQE).…”

“…187,188 Various schemes exist for generating localized orbitals, and for a comprehensive list, please refer to the introduction section of earlier reviews. 245,248 One notable scheme is the introduction of intrinsic atomic and bonding orbitals by Knizia, 249 initially for occupied MOs and later extended to molecular fragments and relativistic spinors 250 as well as to provide additional localized virtuals for correlation and use in time-dependent DFT. 251 The procedure comprises two steps, definition of intrinsic fragment orbitals, followed by localization of the occupied and virtual subspaces by a generalization of the Pipek-Mezey localization algorithm.…”

The relationship between structure and excited-state properties in polyanilines from geminal-based methods

“…Thus, the pCCD-optimized orbitals offer a different viewpoint, in which the information is more compressed, and we have many components in electronic transitions. 93,94 Unlike TD-DFT and CIS, where the electronic transitions are dominated by one main electronic conguration, each electronic transition in EOM-pCCD+S includes several orbital contributions of similar weights but oen of various characteristics (the pCCD orbitals involved in the lowlying excitations are shown in Fig. S10-S18 of the ESI †).…”

Geminal-Based Strategies for Modeling Large Building Blocks of Organic Electronic Materials

“…Thus, the underlying electronic structure differs from the conventional picture we obtain when working with delocalized canonical orbitals such as those predicted by DFAs. The significant advantage of a localized basis , is the clear distinction of the donor and acceptor regions or their interfaces . Electronic excitations can be unambiguously assigned to specific molecular basins, allowing dissection of the electronic excitations into, for instance, charge transfer or local ones, while HOMO and LUMO orbitals can be located on, for instance, donor or acceptor domains.…”