Scott M. Auerbach and Horia I. Metiu,
``Diffusion in zeolites via cage-to-cage kinetics:
Modeling benzene diffusion in Na-Y,''
J. Chem. Phys. 105, 3753-3760 (1996).
Abstract
We have performed kinetic Monte Carlo simulations
of benzene diffusion in Na-Y
(Si:Al=2.0)
over the temperature range 200-500 K.
For hopping on a tetrahedral lattice,
we derive the analytical formula for
D in terms of hopping lengths and times,
yielding the simple-cubic relation
D = ka2/6,
even though the lattice is very different from
simple cubic.
We have
calculated the distribution of cage residence
times for benzene in Na-Y,
finding single
exponential decay controlled by the
SII -> W rate coefficient,
even though several processes contribute to
intercage motion.
Exact agreement between mean square displacement slopes
and ka2/6
is obtained only when using kinetic intercage hopping lengths,
which are found to be in excess of the static length
by as much as 0.54 Angstroms.
Constructing
diffusion coefficients from intercage lengths and times
provides overwhelming computational speedups over calculating
mean square displacements.
Prof SM Auerbach
18 June 2004