Comment on the Compressibility of Cs Determined from Pressure Dependence of Fermi Surface Cross Sections

We report measurements of the angular dependence of the pressure derivatives of cross-sectional areas of the Fermi surface of Cs which vary from 2.67% kbar -1 for the minimum area cross section to 3.30% kbar -1 forH [[111]. This anisotropy invalidates the assumption of free-electron behavior in Cs used by Glinski and Templeton to arrive at a compressibility value for Cs which differed by -14% from that determined from the piston-cylinder measurements of Andersonet al. and by -8% from the ultrasonic result of Kollarits and Trivisonno. While a compressibility derived from our results is admittedly model dependent, we feel there is essentially no inconsistency between our compressibility and those derived by more conventional means.