Abstract:
The Lennard-Jones Devonshire 1 (LJD) single particle theory
for liquids is extended and applied to the anharmonic solid in
a high temperature limit. The exact free energy for the crystal
is expressed as a convergent series of terms involving larger and
larger sets of contiguous particles called cell-clusters. The
motions of all the particles within cell-clusters are correlated
to each other and lead to non-trivial integrals of orders 3, 6,
9, ... 3N. For the first time the six dimensional integral has
been calculated to high accuracy using a Lennard-Jones (6-12) pair
interaction between nearest neighbours only for the f.c.c. lattice.
The thermodynamic properties predicted by this model agree well with
experimental results for solid Xenon.
