Molecular Structure and TD-DFT Study of the Xylene Isomers

In this work, we have investigated the xylene isomers in concepts of vertical and adiabatic ionization energy parameters and molecular orbital insert ignore into journalissuearticles values(HOMO-1, HOMO/SOMO, LUMO, LUMO+1); energies of the neutrals and singly charged cation radicals.  As a first step of the calculations, conformational analysis has been performed for all isomers using the semi-empirical method with PM3 core type Hamiltonian.  Geometry optimization and frequency calculations were performed by using Density Functional Theory insert ignore into journalissuearticles values(DFT); with Becke, three-parameter, Lee-Yang-Parr insert ignore into journalissuearticles values(B3LYP); exchange-correlation functional and 6-311++Ginsert ignore into journalissuearticles values(d,p); basis sets.  UV-Vis electronic spectra of the neutral xylene isomers were calculated by using the TD-DFT method with cam-B3LYP functional and 6-311++Ginsert ignore into journalissuearticles values(2d,2p); basis set.