Related Experiment Video
Updated: Jun 13, 2026

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
The range of electron correlation between localized molecular orbitals. A full configuration interaction analysis for
Laimutis Bytautas1, Klaus Ruedenberg
1Department of Chemistry and Ames Laboratory USDOE, Iowa State University, Ames, Iowa 50011, USA. Laimutis.Bytautas@rice.edu
Abstract:
A many-body expansion of the correlation energy has been formulated in terms of localized molecular orbitals, and the CEEIS (correlation energy extrapolation by intrinsic scaling) method has been used for the evaluation of local full configuration interaction energies in this context. No truncations were applied in the correlating virtual space. With this combination of methods, the full valence CI energy of the molecule NCCN has been calculated within 0.1 mhartree for cc-pVDZ basis sets (configuration space dimension = 10(19)). With appropriate choice of localized orbitals, the many-body expansion was converged to this accuracy with the four-body terms. The individual many-body terms exhibited a rapid decrease with the distance between the localized orbitals. For the orbitals chosen, the conjugated triple bonds presented no problems. The analysis of the various contributions furnishes rigorous quantitative ab initio benchmarks for the range of intramolecular electron correlations.
More Related Videos
08:54Vibrational Spectra of a N719-Chromophore/Titania Interface from Empirical-Potential Molecular-Dynamics Simulation, Solvated by a Room Temperature Ionic Liquid
Published on: January 25, 2020
16:11Thermochemical Studies of Ni(II) and Zn(II) Ternary Complexes Using Ion Mobility-Mass Spectrometry
Published on: June 8, 2022
Related Concept Videos
Molecular Orbital Theory I
MO Theory and Covalent Bonding
Molecular Orbital Theory II
π Molecular Orbitals of the Allyl Cation and Anion
¹H NMR: Long-Range Coupling
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.
Valence Bond Theory and Hybridized Orbitals
A σ bond (single bond in a Lewis structure) is a covalent bond in which the electron density is...