Computational Results
The calculations in this work were performed using Forcite module in
Materials Studio.17 To
calculated the interaction energy between LAB isomers and zeolite, we
first build a cleaved model with the bowl shape structure exposed on the
surface to provide effective adsorption space. This model was optimized
with energy, force, displacement convergence thresholds set to
1×10-4 kcal/mol, 5×10-3 kcal/mol/Å
and 5×10-3 Å, respectively. The van der Waals
interaction between the atoms was modeled using universal force field,
while the electrostatic interaction was described with atomic partial
charges calculated using QEq method and summed with Ewald method. The
van der Waals interaction was truncated within a cutoff distance of 15.5
Å, and the Ewald accuracy for computing electrostatic interaction was
set to 1×10-4 kcal/mol. After the optimization, one
molecule of the LAB isomers was respectively adsorbed in the bowl shape
structure of the model as an adsorbed configuration. These
configurations were sequentially optimized with the same parameters as
optimizing the bare model. Finally, using the same parameters to
describe van der Waals interaction and electrostatic interaction, we
calculated the single point energy of these adsorbed configurations, the
bare adsorbent model and the LAB isomers, and obtained the binding
energy using Eq.1,
Ebinding = Econfiguration -
Ebare model - ELAB (1)