# Reduced Two-Electron Interactions in Anharmonic Molecular Vibrational Calculations Involving Localized Normal Coordinates

journal contribution

posted on 04.06.2021, 22:13 by Magnus W. D. Hanson-HeineSpatially
localized vibrational normal mode coordinates are shown
to reduce the importance of calculating the full set of two-electron
terms in the molecular electronic Schrödinger equation. Electron
correlation and dispersion interactions become less significant in
(

*E*,*E*)-1,3,5,7-octatetraene vibrational self-consistent field calculations when displacing remote atoms along multiple coordinates. Electron correlation interactions between spatially remote modes are also found to be less important compared to their corresponding uncorrelated interaction terms. Attenuation of the Coulomb operator indicates that the two-electron terms between remote electrons become less important for accurately describing the strongly contributing mode-coupling terms between sets of localized vibrational modes.