An Intermolecular Potential for Accurate Description of the Properties of 12-Ring Siliceous Zeolites

The
modified Hill–Sauer force field (mHSFF) proposed by
Sholl and co-workers for the 8-membered ring (MR) siliceous zeolite
has been modified by tuning the θ0 of ∠Si–O–Si
and ∠O–Si–O and partial charges on Si and O to
describe the window size of 12 MR siliceous zeolite more accurately.
Proper temperature-dependent trend in minimum window size distribution
was obtained using our newly proposed force field (aHSFF-G), which
was further underpinned by ab initio density functional
theory (DFT) calculation using the PBE functional. The average cell
parameter computed using aHSFF-G is in better consonance with the
experimental data. Simulations in the Parrinello–Rahman formulation
(Molecular dynamics simulation) were carried out on siliceous faujasite
using mHSFF and aHSFF-G to examine the volume and the lattice parameter
variations of the simulation shell. The temperature dependence of
volume and thermal expansion coefficient were evaluated as another
test of accuracy. The transferability of aHSFF-G was examined on 5
experimentally known 12 MR siliceous zeolites.