  In this work, we have carried out molecular dynamics (MD) simulation
techniques to study the diffusion coefficient of interlayer molecules at
different temperature. Within the wider context of water dynamics in soils, and
with a particular emphasis on clays, we present here the translational dynamics
of water in clays, in a bi-hydrated states. We focus on temperatures between
293 K and 350 K, i.e., the range relevant to the environmental waste packages.
A natural hectorite clay of interest is modified as a synthetic clay, which
allows us to understand the determinantal parameters from MD simulations
through a comparison with the experimental values. The activation energy E a
determined by our simulation is [8.50 - 16.62] KJ/mol. The calculated diffusive
constants are in the order of 10^{-5} {cm^{2}}/s. The simulation results are in
good agreement with experiments for the relevant set of conditions, and they
give more insight into the origin of the observed dynamics.
