CHARGE ITERATED PARAMETERS FOR EXTENDED HUCKEL CALCULATIONS ON POLYTETRAFLUOROETHYLENE - RELEVANCE TO X-RAY PHOTOELECTRON-SPECTROSCOPY

Tight-binding band calculations of the extended Huckel type were performed on polytetrafluoroethylene in order to probe the effect of the atomic orbital parameters on the bonding in the polymer. Comparison was made with previous extended Huckel and ab initio calculations, as well as with experimental data. It was found that the original parameterization of Hoffmann makes the C-F bond too polar and should be corrected, as prescribed by Gray. With these corrections, the Hoffmann formulation for extended Huckel calculations allows a reasonable, albeit approximate, simulation of the X-ray photoelectron spectrum.