Related Experiment Video
Updated: Jun 26, 2026

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
A Cautionary Tale: Failure of the Valence CASSCF to Describe the Hallmark of Hydrogen Bonding
Long H Nguyen1, Thom H Dunning1,2, Sotiris S Xantheas1,2,3
1Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Abstract:
Valence CASSCF (vCAS) calculations for (H2O)2, (HF)2, and HF-H2O dimers fail to capture donor bond lengthening and associated redshift of its stretching frequency due to hydrogen bonding. Analysis of the orbitals in the vCAS calculation reveals that one of the active weakly occupied dimer orbitals correlates electrons in the acceptor lone pairs, not the donor bond, which is left without left-right correlation. This has significant implications for subsequent treatments of dynamical correlation that are based on a vCAS reference wave function.
More Related Videos
Related Concept Videos
Valence Bond Theory
Valence Bond Theory
Hydrogen Bonds
Hydrogen Bonds
Covalent Bonding and Lewis Structures
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...

