Multireference Averaged Quadratic Coupled Cluster (MR-AQCC) Study of the Geometries and Energies for ortho-, meta- and para-Benzyne
Year: 2024
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide The diradical benzyne isomers are excellent prototypes for evaluating the ability of an electronic structure method to describe static and dynamic correlation. The benzyne isomers are also interesting molecules with which to study the fundamentals of through-space and through-bond diradical coupling that is important in so many electronic device applications. In the current study, we utilize the multireference methods MC-SCF, MR-CISD, MR-CISD+Q, and MR-AQCC with an (8,8) complete active space that includes the σ, σ*, π and π* orbitals, to characterize the electronic structure of ortho-, meta- and para -benzyne. We also determine the adiabatic and vertical singlet–triplet splittings for these isomers. MR-AQCC and MR-CISD+Q produced energy gaps in good agreement with previously obtained experimental values. Geometries, orbital energies and unpaired electron densities show significant through-space coupling in the o - and m -benzynes, while p -benzyne shows through-bond coupling, explaining the dramatically different singlet–triplet gaps between the three isomers.
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Awards: G1834818601, G235671070, G2445275399, Acquisition of High Performance Computers for the Northeastern Undergraduate Research Chemistry Consortium, G3804823648, G4194822168, RUI: A Theoretical Investigation of Multireference Diradical Molecules, RUI: Collaborative Research: Multireference Studies of Organic Polyradicals, Radical Reactions and Graphene Nanoribbons, G7731961781, RUI: Characterizing Pyrolysis and Combustion Pathways for Asphaltene Model Compounds, Collaborative Research: Aggregation Mechanisms in Carbon Nanomaterials Based on Pi-conjugated Polycyclic Aromatic Hydrocarbons, Acquisition of a Linux Cluster for the Molecular Education and Research Consortium in Undergraduate Computational Chemistry (MERCURY)
OpenAlex ID: W4402309524