A molecules reactivity is predominantly determined by the electronic structure of the molecule. Vibrational frequency, polarizability, dipole moment, tendency to donate electrons and absorption of visible light are all useful properties of molecules that can be found using computer molecular orbital quantum mechanic calculations. The computer calculations ran off the basis that the lowest energy of the molecule is the most stable and therefore the best or optimized geometry of that molecule. The computer employs the variational theorem which approximates the true wavefunction with the sum of the trial wavefunctions. Molecules larger than a few atoms used to be unattainable but with the advance of high processing computers larger molecules can now be determined. The methods AM1 and PM3 use empirical data to calculate the expectation value of energy. This makes them fast and easy but the better method is ab inito. This includes 6-21G, 6-31G, 3-21G, and DZV. The size of these basis sets is much larger than AM1 and PM3 and is therefore more accurate. DZV is the largest and should give the best results. 

In this experiment GAMESS was used to calculate the optimized geometry, dipole moments, bond lengths and angles, and vibrations for Bromine, Hydrogen Peroxide, and m-xylene. The PM3, 6-21G, 6-31G and DZV basis sets were used for Hydrogen Peroxide and m-xylene. Bromine used the same basis sets except it was not optimized for 6-21G so 3-21G was used instead. Jmol was then used to visualize the results of the GANESS computations.