Semi-empirical modeling of the optical gap of amorphous hydrogenated nitrogenated carbon films

We report here results of modeling the optical gap of amorphous hydrogenate d nitrogenated carbon films using semi-empirical methods. Parametric Method 3 (PM3) was used to optimize the geometry of oligomers. Using the PM3 geom etrical data, Zerner's intermediate neglect of differential overlap calcula tions were carried out to simulate the absorption spectra of the films. We have analyzed the optical gap values as a function of the geometry and elem ental composition of these materials. The theoretical results are contraste d with the experimental ones and used to estimate the actual conformations of the amorphous materials. The results indicate that this approach can be an efficient tool to analyze amorphous carbon films. (C) 2000 American Vacu um Society. [S0734-2101(00)08705-4].