Quantum Films

We use state of the art theoretical and computational techniques and tools to study various equilibrium
as well as dynamical properties of quantum systems confined in restricted dimensionality
(such as the one of film) or in restricted geometries.

During the past year we have found a number of very interesting properties of such systems
where simple and well known van der Waals forces govern the atom-atom interactions.
The growth of the most idealized films, such as those of hydrogen and helium on various
substrates where the growth parameters are under control, provides us the understanding
of the growth process for more complicated quantum films.

For example for the case of helium or hydrogen films, as a function of the coverage
of helium or hydrogen we can explain several features of the measured and calculated
specific heat,  compressibility, superfluid density. The films goes through a number of
very different phases such as various commensurate solids, incommensurate solids,
superfluid phases, two-dimensional clusters, etc. The onset of these phases, the
promotion densities, the peaks of the specific heat, the behavior of the period shifts
in the torsional oscillator experiments are all reproduced in excellent agreement with
experiment starting from the known values of fundamental constants and with no free
parameter.  We shall continue these studies mainly for hydrogen on graphite
where there are interesting experimental results and for helium on graphite
preplated by a few layers of hydrogen.