  We present results of lattice dynamics calculations of Poisson's ratio (PR)
for solid hydrogen and rare gas solids (He, Ne, Ar, Kr and Xe) under pressure.
Using two complementary approaches - the semi-empirical many-body calculations
and the first-principle density-functional theory calculations we found three
different types of pressure dependencies of PR. While for solid helium PR
monotonically decreases with rising pressure, for Ar, Kr, and Xe it
monotonically increases with pressure. For solid hydrogen and Ne the pressure
dependencies of PR are non-monotonic displaying rather deep minimums. The role
of the intermolecular potentials in this diversity of patterns is discussed.
