The cumulant method in diffraction analysis of polyatomic molecules

Abstract A method of analysis of molecules by electron diffraction in terms of the intramolecular potential function is presented. The method is based on the cumulant representation of the molecular scattering function and a perturbation solution of the vibrational problem. Special care has been taken in difficulties involving Fermi resonances. A test of the performance of the devised theory is provided by comparison of the calculated temperature dependence of r a distances in SF 6 with available experimental data. The proposed scheme of diffraction analysis, providing due facility for incorporation of relevant spectroscopic information, is checked by treatment of published intensity data for SO 2 and SF 6 .