Spin contamination of simple hydrocarbon systems: A comparison
between Hartree-Fock and Density Functional Theory calculations.
Shukri Sulaiman, Mohamed Ismail Mohamed Ibrahim, and Ang Lee Sin
School of Distance Education, Universiti Sains Malaysia, Penang, Malaysia
The results on a series of first principles calculations performed on three hydrocarbon
systems, (C10H8, C24H12, and C36H16), using Hartree Fock and density functional theory, will be
presented. Except for naphthalene, Hartree-Fock based calculations resulted in severe
contamination in all systems, while in density-functional based calculations, spin contamination
is found to be negligible. The results agree with the findings of Montoya et al. [1]. It can be
shown through the graphical representations that there were noticeable differences in densities
from these two methods. Results from MP2 calculations will also be included for comparison.
[1] Alejandro Montoya, Thanh N. Truong, and Adel F. Sarofim, Spin contamination in HartreeFock and density functional theory wavefunctions in modeling of adsorption on graphite, J. Phys.
Chem. A, 104 (26), 6108 - 6110, 2000.