A modified Xα-SCF method is proporsed for calculating atomic structure parameters of a molecule and further characterization or calculation of some other properties of a molecule could be performed based on the calculated parameters.The method could be used to calculate the atomic parameters in different enviroments. Since the basic parameters as wavefunctions, radial distribution functions and scattering factors were known by the calculation, the method in fact can be extended to the calculation of various atomic structural parameters. In addition, the calculation could be carried out by a micro-computer, it is time-saving, and the calculation results are comparable with those from the ab initio method.
Independent atom model (IAM) is generaly used in gaseous electron diffraction (GED) experiment. This means that the effect of the charge redistribution in a molecule is neglected in general case in GED data analysis and the information of the effect could be taken from the residual intensity.In this work, various methods were suggested to calculate the elastic scattering factors for S, F atoms in SF6 molecule (modified IAM or MIAM) and the residual intensity of 40keV electrons scattered by the same molecule. Bonham-type parameter method was selected to acheive good agreement with experimental results and the charge redistribution was determined according to these parameters. Further comparison was made between different methods and their results.
