Abstract
The non-orthogonal configuration interaction with fragments (NOCI-F) approach is extended opening the possibility to study intramolecular processes and materials with covalent or ionic lattices. So far, NOCI-F has been applied to study intermolecular energy and electron transfer employing ensembles of fragments that do not have atoms or bonds in common. The here presented approach divides the target system into two overlapping fragments that share one or more atoms and/or one or more bonds. After the construction of a collection of (multiconfigurational) fragment wave functions in a state specific optimization procedure, the fragment wave functions are combined to form many-electron basis functions for the non-orthogonal configuration interaction of the whole system. The orbitals in the overlapping fragment are defined by a corresponding orbital transformation of the fragment orbitals through a singular value decomposition. The overlapping fragments approach is first illustrated for a model system and then used to highlight some possible applications of NOCI with overlapping fragments. The results of excited state diffusion in transition metal oxide, intramolecular singlet fission and magnetic interactions in organic biradicals and ionic compounds are discussed.
| Original language | English |
|---|---|
| Pages (from-to) | 15163-15175 |
| Number of pages | 13 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 27 |
| Issue number | 28 |
| DOIs | |
| State | Published - Jun 30 2025 |
Funding
Financial support was provided by the Ministry of Science and Innovation of the Spanish administration through the projects PID2021-126076NB-I00, PID2023-148238NB-I00, and Maria de Maetzu CEX2021-001202-M and by the Generalitat de Catalunya through the projects 2021SGR00079 and 2021SGR00110. This work used resources of the Oak Ridge Leadership Computing Facility (OLCF) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy (DOE) under Contract DE-AC05-00OR22725 through the INCITE Project CHM154 and SummitPLUS Project CHM198. Part of the calculations were performed on Leonardo@CINECA (Italy) within the EuroHPC-JU programme. This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (https://energy.gov/downloads/doe-public-access-plan).