Barrier energy for the b. c. c.-f. c. c. martensitic transition in sodium

Abstract
Using an Ashcroft empty-core model pseudopotential, we have calculated the binding energy of the intermediate structures between b. c. c. and f. c. c. sodium at zero temperature for two homogeneous-deformation reaction-path models, namely those of Bain (1924) and Zener (1948). Bain's model gives a lower barrier energy than that of Zener : 9·2 K per atom, much lower than a previous estimate based on the second-order elastic constants.