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Fractional Occupation Numbers and SIC-Scaling Methods with the Fermi-Lowdin Orbital SIC Approach

revised on 30.01.2020, 18:32 and posted on 31.01.2020, 07:00 by Fredy W. Aquino, Ravindra Shinde, Bryan Wong
We derive an alternate expression for the Fermi-Lowdin Orbital Self-Interaction Correction (FLO-SIC) energy gradient and re-visit how the FLO-SIC methodology can be seen as a constrained unitary transformation acting on canonical Kohn-Sham orbitals. We present a new performance and accuracy analysis of the FLO-SIC approach, which we have recently implemented in the massively-parallelized NWChem quantum chemistry software package. Our FLO-SIC implementation has been tested for the prediction of total energies, atomization energies, and ionization potentials of small molecules and relatively large aromatic systems. The ionization potentials of multi-electron systems are calculated with the adaptation of fractional occupation numbers within FLO-SIC. We also carefully examine the possible improvements of these predictions with various SIC scaling methods based on kinetic energy densities and gradients of electronic densities.


U.S. Department of Energy, Office of Science, Early Career Research Program under Award No. DE-SC0016269


Email Address of Submitting Author


University of California, Riverside


United States

ORCID For Submitting Author


Declaration of Conflict of Interest

no conflict of interest