Tests of current models of intermolecular potentials against x-ray diffuse scattering in C 60
Résumé
Diffuse scattering, which contains two-body information, is a rich source of knowledge on the interactions between the C 60 molecules. We present a mean-field theory for calculating the diffuse scattering in the high-temperature phase of C 60 from microscopic models of intermolecular interactions. The diffuse scattering is calculated and discussed for most of the models available to date. It is compared with single-crystal x-ray diffuse scattering data. Overall, the positions of the diffuse scattering maxima, corresponding to competing instabilities, are found to be independent of the model of interactions. This suggests that these instabilities are related to the shape of the large C 60 molecule. No model is fully satisfactory for fitting the relative intensities of the diffuse scattering features. The best fit is obtained with the Lamoen-Michel model, which accounts also correctly for the Bragg peak intensity in the high-temperature phase. The physics of the models is discussed and some improvements are proposed.
Domaines
Autre [cond-mat.other]Origine | Fichiers éditeurs autorisés sur une archive ouverte |
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