Molecular calculations of NO, NO2 and Anisole
Jen Schauer and Liem Nguyen

    The reactivity and stability of a molecule depend mainly on its electronic structure and properties, which include the locations of electrons, available energy levels, vibrational frequencies, dipole moments and UV- Visible spectrum. These properties can be modeled mathematically and computed using computer programs. The calculations are complicated and could require a great amount of time for large molecules. So far ab initio is the best theory for these quantum calculations.
    The three molecules of interest in this experiment were NO, NO2 and anisole. The calculation formulated each molecule with a basis set, which is a combination of normalized wavefunctions. Some basis sets commonly chosen are 321G, 631G and DZV (Double Zeta Valence), which were used in the experiment. With the specific basis set, optimized geometry for the molecule was determined and other properties such as HOMO orbitals, vibrational frequencies, bond lengths and angles were obtained. Finally, using surface energy calculations, a bond strech and potential energy was plotted and UV- visible spectrum of each molecule was obtained and compared to literature values.


     In WebMO Job Manager, the molecule (NO, NO2 or anisole) was built and ran an intitial geometry optimization with either basic set AM1 or STO3G. An input file was generated WXMacMolPlt from the first calculation to run other geometry optimization of higher basic set (3-21G, 6-31G and DZV) in the compiler GTK Gamess. Once the geometry optimization was obtained, vibrational energy calculations were done. In Jmol the optimized molecule with bond lengths and angles were displayed for each level theory and export to a webpage template. The HOMO orbital of each molecule as the animation of main vibrational frequencies were also exported using Jmol.
    Surface energy calculations were run to examine the change in potential energy due to bond stretching for each level theory. In Igor, a graph of potential energy vs bond stretching was plotted for each basis set and compared.

Click to see three molecular calculations: NO, NO2, and anisole
 1 Vibrations. Experimental vibrational data for a given species. NO,NO2.
 2 .  Geometries. Experimental geometry data for a given species.  NO,NO2.
 3 Spetcra Database For Organic Compound. Anisole IR Spectrum.