The authors propose a novel approach to the problem of polarizabilities and dissociation in electric fields from the static limit of the Vignale-Kohn (VK) functional. The response to the purely scalar part of the VK response potential is considered. This potential has ground-state properties that notably improve over the full VK response density and over usual (semi-)local functionals. The correct qualitative behavior of our potentials means that it is expected to work well for polarizabilities in cases such as the H(2) chain, and it will also correctly dissociate open-shell fragments in a field.
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http://dx.doi.org/10.1063/1.2741243 | DOI Listing |
J Chem Phys
January 2025
Laboratory of Theoretical Chemistry, Institute of Chemistry, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, Budapest H-1117, Hungary.
Single-Molecule Junctions (SMJs) are key platforms for the exploration of electron transport at the molecular scale. In this study, we present a method that employs different exchange-correlation density functionals for the molecule and the lead domains in an SMJ, enabling the selection of the optimal one for each part. This is accomplished using a formally exact projection-based density-functional theory (DFT-in-DFT) embedding technique combined with the non-equilibrium Green's function method to predict zero-bias conductance.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K.
Classical reaction barriers in density-functional theory are considered from the perspective of the density-fixed adiabatic connection. A 'reaction adiabatic-connection integrand', , is introduced, where λ is the electron-electron interaction strength, for which equals the barrier, meaning the barrier can be easily visualized as the area under a plot of vs λ. For five chemical reactions, plots of reference , calculated from Lieb maximizations at the coupled-cluster level of theory, are compared with approximate , calculated from common exchange-correlation functionals using coordinate scaling, for coupled-cluster densities.
View Article and Find Full Text PDFJ Phys Chem Lett
December 2024
Theoretical Chemistry Group, Molecular Chemistry, Materials and Catalysis Division (MOST), Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Place Louis Pasteur 1, B-1348 Louvain-la-Neuve, Belgium.
Simplified quantum chemistry (sQC) methods can routinely compute excited states for very large systems in an "all-atom" fashion. They are viable alternatives to regular multiscale schemes. sQC methods have the advantage of accounting explicitly for all of the environment at a quantum mechanical (QM) level.
View Article and Find Full Text PDFMolecules
November 2024
Institute of Physics, University of Rzeszów, 35-310 Rzeszów, Poland.
The main purpose of this study is to characterize the nature of the low-energy singlet excited states of the anthranilic acid homodimer (AA) and their changes (symmetry breaking) caused by deformation of the centrosymmetric, ground state structure of AA towards the geometry of the S state. We employ both the correlated ab initio methods (approximate Coupled Clusters Singles and Doubles-CC2 and CASSCF/NEVPT2) as well as the DFT/TDDFT calculations with two exchange-correlation functionals, i.e.
View Article and Find Full Text PDFJ Comput Chem
January 2025
School of Physics, The University of Sydney, Sydney, New South Wales, Australia.
Using first principles calculations we investigate cobalt-coordinated tetracyanoquinodimethane (R-CoTCNQ) as a potential catalyst for the CO electroreduction reaction (COERR). We determine that exchange-correlation functionals beyond the generalized gradient approximation (GGA) are required to accurately describe the spin properties of R-CoTCNQ, therefore, the meta-GGA rSCAN functional is used in this study. The free energy COERR reaction pathways are calculated for the reduced catalyst ([R-CoTCNQ]) with reaction products HCOOH and HCHO predicted depending on our choice of electrode potential.
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