Electron diffraction analysis of XY2 and XY3 molecules with large amplitude motion: Part I. Dynamical model and molecular scattering functionстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:A simplified consideration of curvilinear effects in diffraction analysis of nonrigid molecules with one large amplitude coordinate is presented. It is shown that energy barrier estimates in practice do not suffer from neglect of curvilinear effects in the coordinate distribution function. However, the situation is not so favorable for the positions and shapes of the large amplitude potential function in the extrema regions.
The effect of large amplitude motion upon diffraction intensity of the XY2 molecule is considered from the standpoint of the theory developed by Hougen, Bunker and Johns which allows for large displacements of the bending coordinate and considers both of the large contributions to the potential and kinetic energy parts of the vibration-rotation Hamiltonian. This Hamiltonian is used to derive explicit expression for sM(s) in terms of the molecular potential function.
The vibration-rotation Hamiltonian modified for use with four-atomic molecules taken from the literature is applied to formulate a similar treatment of XY3 molecules exhibiting large amplitude inversion motion.
It is demonstrated that the vibration-rotation theory of Hougen, Bunker and Johns provides a straightforward basis for an accurate relation of the molecular potential function to intensity of scattering which meets the need for the refinement of diffraction analysis procedures for nonrigid systems.