Previous abstract
Next abstract
Session E27 - Materials Theory - Simulations II General.
MIXED session, Tuesday morning, March 19
Room 127, America's Center
A theoretical investigation of the Gibbs free energy and molar volume of solid ^3He and ^4He will be presented. The helium solids are quantum crystals for which the kinetic energy is comparable to the potential energy and their molar volumes exhibit a striking departure from the values expected for the theoretical closed-packed arrangements based on the known atomic radii. In the present model, the potential energy between the helium atoms is taken to be of the Lennard-Jones form and treated on the same footing as the kinetic energy. The internal energy is obtained by solving a one-dimensional Schrödinger equation directly using a method that transforms the equation into a matrix eigenvalue problem. The molar volume is then obtained by minimizing the Gibbs free energy at a given pressure. It is found that the molar volume of ^4He is 26.9 cm^3/mol at a pressure of 30 atmosphere, corresponding to an interatomic distance 1.43 times the classical expected value, in reasonable agreement with experiment.
