Ab initio and DFT studies on structure and stability of dimethylhalogenoethene molecules

Abstract

Molecular structure and conformational stability of the isomers of dimethylhalogenoethene with fluorine, chlorine and bromine as the substituents, have been studied using ab initio and density functional theory studies. The molecular geometries were optimized using HF, MP2, B3LYP and B3PW91 levels of theory implementing 6-31G* basis set. To study the localized electronic features of the molecules, single point energy calculations have been carried out at MP2/6-31G* level of theory by varying the torsion angle from 0 to 120° in steps of 20°. The chemical hardness and chemical potentials are calculated and the maximum hardness principle is tested for these molecules. Using the relative energy and chemical hardness the relative stability of the isomers are studied. The rotational constants and dipole moments are calculated at all the four levels of theory and used to study the stability of the molecule.