Date of Award

2021-08-01

Degree Name

Master of Science

Department

Computational Science

Advisor(s)

Rajendra Zope

Second Advisor

Tunna Baruah

Abstract

The Kohn–Sham formulation of density functional theory (DFT) is a widely used quantum mechanical theory to study chemical and materials properties. The practical application of DFT requires an approximation to the exchange–correlation (XC) functional. These approximations suffer from self-interaction errors due to the incomplete cancellation of the self-Coulomb energy with the approximate self-exchange and correlation energy for one-electron densities. Systems with weakly-bound electrons impose great challenges to semi-local density functional approximations. We use recently developed local scaled self-interaction correction (LSIC) by Zope et al and the Perdew-Zunger SIC method using the Fermi-Löwdin orbitals to calculate the vertical detachment energies (VDEs) of ammonia cluster anions. The results from the density plot difference show that these clusters bind the extra electron in dipole-bound states. The LSIC significantly reduces the errors in LDA and GGA calculations leading to better agreement with reference Coupled-Cluster with Single and Double and Perturbative Triple excitations CCSD(T) values. We also investigate the negative of highest occupied molecular orbital (HOMO) energy with DFA, FLOSIC, and LSIC to approximate the VDEs.

Language

en

Provenance

Recieved from ProQuest

File Size

49 p.

File Format

application/pdf

Rights Holder

Peter Obinna Ufondu

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