Related Experiment Video
Updated: May 27, 2026

Measurements of Long-range Electronic Correlations During Femtosecond Diffraction Experiments Performed on Nanocrystals of Buckminsterfullerene
Published on: August 22, 2017
On the nature of electron correlation in C60
David Stück1, Thomas A Baker, Paul Zimmerman
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Abstract:
The ground state restricted Hartree Fock (RHF) wave function of C(60) is found to be unstable with respect to spin symmetry breaking, and further minimization leads to a significantly spin contaminated unrestricted Hartree Fock (UHF) solution ( = 7.5, 9.6 for singlet and triplet, respectively). The nature of the symmetry breaking in C(60) relative to the radicaloid fullerene, C(36), is assessed by energy lowering of the UHF solution, , and the unpaired electron number. We conclude that the high value of each of these measures in C(60) is not attributable to strong correlation behavior as is the case for C(36). Instead, their origin is from the collective effect of relatively weak, global correlations present in the π space of both fullerenes. Second order perturbation (MP2) calculations of the singlet triplet gap are significantly more accurate with RHF orbitals than UHF orbitals, while orbital optimized opposite spin second order correlation (O2) performs even better.
Related Concept Videos
π Electron Effects on Chemical Shift: Overview
π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
Electron Configurations
The relative energies of the subshells determine the order in which atomic orbitals are filled (1s, 2s, 2p, 3s, 3p, 4s,...
Electron Orbital Model
The first shell is closest to the nucleus, and it has only one subshell with a single spherical orbital called the...
MO Theory and Covalent Bonding
Molecular Orbital Theory I

