A phenomenological approach for the phonon dispersion curves of barium
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A phenomenological model which combines the axially symmetric ion-ion interaction with the electron-ion interaction scheme of Bhatia has been successfully used to calculate the phonon dispersion curves of bcc Ba. In particular, when the elastic constants determined by Mizukiet al are used as input data, the model successfully reproduces the anomalous feature of the dispersion curves measured by them. On the other hand, when the elastic constants determined by Buchenauet al are used, the model produces a cross over of the longitudinal and transverse branches in the  direction, a feature not established in their measurements. Thus the features of the dispersion curves in the  direction which is due to the hybridization of thes andd states are evident in the measured elastic constants and are consistent with the values of C12-C44.
KeywordsPhenomenological model phonon frequencies barium
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