The present work deals with the electronic properties of organic molecules in form ring,
containing semiconductor atoms. Cyclobutadiene is the original ring before replacing
the hydrogen atom by hydroxyl radical. Density functional theory with B3LYP/6-21G
level has been used to find the electronic structure and electronic properties of the
studied molecules. The effect of substitute on cyclebutadiene molecule is discussed on
the basis of the calculated electronic properties. It is included total energy, energy gap,
ionization potential, electronic affinity and electrophilicity, with comprehensive
analysis of the calculated highest-occupied and lowest-unoccupied orbital (HOMO and
LUMO respectively) energies. The results in this study show that the calculated
electronic properties for cyclebutadiene have been found a good agreement with the
previous studies. For other molecules, we have not found a reference data, so this study
supplies a new data in this aspect. These calculations have been performed using
Gaussian 03 package.