Electron Binding Energy of Polar Molecules Using Fermi Lӧwdin Orbital Self Interaction Corrected Density Functional Scheme
Density functional theory (DFT) has become a standard method for electronic structure calculations in physics. The standard approximate density functional usually do not bind this class of anions, due to self-interaction error (SIE). We apply the recently developed Fermi Lӧwdin orbitals based self-interaction correction method (FLOSIC) with long-range diffuse Gaussian functions to study dipole bound anions and negatively charged water clusters. These calculations are carried out using Perdew-Wang (1992) local spin density PW91-LDA, Perdew-Burke-Ernzerhof PBE-GGA, and the recently developed Strongly Constrained and Appropriately Normed SCAN-meta-GGA functional which satisfies all the known constraints for exchange-correlation functional. Plot from FLOSIC density difference shows that the excess electron is weakly bound to the molecule and mostly occupies a very diffuse orbital away from the molecular framework. In the water cluster anions, the extra electron is not bound to any of the water molecules but rather occupies a diffuse orbital. We find that applying FLOSIC brings the LDA, GGA, and SCAN results closer to experimental values for the carbonate molecules. The calculated binding energy give an absolute deviation of 0.41meV for EC at PBE-GGA and 1.95meV for VC at PW91-LDA which agrees with experimental values. LDA functional show slightly larger binding energy in all cases. The water cluster anions, binds in all level with the FLOSIC GGA with the least mean absolute deviation MAD of 60.1meV relative to CCSD(T).
Ufondu, Peter Obinna, "Electron Binding Energy of Polar Molecules Using Fermi Lӧwdin Orbital Self Interaction Corrected Density Functional Scheme" (2019). ETD Collection for University of Texas, El Paso. AAI22592445.