Electronic structure and quadrupole couplings of the heterocycles 2-imidazolidinone, 2-imidazolidinethione and 2-imidazolidineselenone by the MS-LDA method

Abstract

Multiple-scattering local-density-approximation (MS-LDA) calculations, with both Xα and Vosko–Wilk–Nusair (VWN) exchange-correlation functionals, have been performed on the ring compound 2-imidazolidenone and its sulphur and selenium analogues. Calculated ionization potentials were insensitive to the functional choice and agreed better with experiment than previous studies by other methods. Nitrogen nuclear quadrupole coupling constants were computed; these were sensitive to the functional choice, the VWN coupling constant being consistently lower than the Xα coupling constant. The principle moment, q_zz, was in good agreement with experiment: the Xα and VWN results bracketed experiment. However, the asymmetry parameters, η, were not well predicted. Trends along the series paralleled experimental results.