Phonon frequencies of cesium

Potential energy functions for atomic solids

“…rmin = 0"8re). Frequencies from [28][29][30][31][32][33] respectively for Li, Elastic constants from [6]. Lattice constants (q) and energies (U) from t I dyncm -2 = 10 -l Nm -2.…”

“…For Cs the experimental data are limited to only three phonon frequencies; the threefold degenerate L + 2T branch frequencies at (1,0, 0) and (1/2, 1/2, 1/2) and the L branch frequency at (1/2, 1/2,0) [33]. We have also used values for the L and T branches at (0.3, 0.3, 0-3) and (0.7, 0.7, 0-7) and for Tl and/'2 at (0-5, 0"5, 0) that have been deduced by Ramamurthy and Satishkumar by applying a scaling rule to the frequencies of the lighter alkali metals [32]. Our curves for Cs therefore have predictive capability.…”

Lattice Dynamics of Alkali Metals

“…Ramamurthy and Satishkumar [7,8] have shown by analysing these phonon frequencies that the observed crossover of the [EOO] branches in lithium is not en anomalous property, but manifests itself only in alkali metals of smaller atomic mass and interatomic distance while it degenerates into overlapping in others. For the first time, these authors [9] have deduced a reliable set of phonon frequencies of cesium along the principal symmetry directions which are homologous with t h e corresponding experimental frequencies of other alkali metals. Besides, Ramamurthy and Singh [lo] and Satishkumar [ l l ] have succeeded in reproducing the crossover in lithium with a large positive value of the electron gas constant by making use of five-constant and six-constant axially symmetric models, respectively.…”