Singlet–Triplet Gap in Covalently and Weakly Bound Carbenes: Studying the Dependence on the Exchange–Correlation Functional
Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide We systematically analyze here the performance of density functional approximations for the calculation of the singlet–triplet gap of covalently bound carbenes (i.e., substituted arylcarbenes of increasing size and with different electroactive substituents) and weakly bound carbenes (diphenylcarbene noncovalently interacting with H 2 O, CH 3 OH, ClCF 3, BrCF 3, and ICF 3 molecules). The calculations revealed an unexpected functional dependence, in the sense that low levels of the functional hierarchy (e.g., BLYP or PBE) provide lower errors than more sophisticated functionals (e.g., hybrid and double-hybrid expressions), thus evidencing a subtle yet marked interplay between the ingredients of any modern exchange–correlation functional. The decomposition of the results as a function of those ingredients allowed us to isolate those functionals overestimating (by default) the energy stability of the triplet state and how (nonempirical) formulations of double-hybrid functional are able to cope with that initial bias. We recommend double-hybrid functionals (e.g., PBE-QIDH) to get robust and sufficiently accurate results (averaged deviation of ±1–2 kcal/mol with respect to reference results) for other applications and studies involving these challenging carbene species.
Source: ACS Omega
Institutions: University of Alicante, Centre National de la Recherche Scientifique, Université Paris Cité, Interfaces Traitements Organisation et Dynamique des Systèmes, Chimie ParisTech - PSL, Université Paris Sciences et Lettres, Chimie Biologique pour le Vivant, Institute of Chemistry for Life and Health Sciences
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,935
Awards: G1522837894, G1523488774, Modeling the Molecule-Plasmon Coupling with Electronic Structure Method, G2262748287, G2459521437, G277089799, G3480869486, G3543459289, G3681454997, G4042783231, G425668148, G4268814097, G4386190359, G464105488, G4656594441, G696853029, G7084143925, G7240651115, G7376787254, In-silico Models for the Design of Mechanochromic Functionalized Polymers, G8013019944, Université de Paris
OpenAlex ID: W4415282030