Intraframework potential energy function of zeolites

Monte Carlo Simulations of Ne, Ar, Kr, and Xe Encapsulated in Cs3Na9−A Zeolite

“…In our previous work, the potential energy function for the interaction between the zeolite A framework and the ion bound to it was proposed. , The potential function reproduced well the X-ray crystal structures of various kinds of ion-exchanged zeolites. The purpose of this work is to calculate the energy distribution and the structure of inert gases Ne, Ar, Kr, and Xe, which are encapsulated in a Cs 3 Na 9 −A zeolite at several temperatures and various loading conditions.…”

“…Since there are three different Na-binding sites in the A-type zeolite, the average value of the Na net atomic charges was taken. In our previous work, , it was determined to be +0.625 e from normal mode analysis results . Since the electronegativity of the Cs ion is not much different from that of Na + , the net atomic charge assigned to the Cs ion was the same as that of the Na ion.…”

“…The framework was assumed to be rigid throughout the calculation. The fractional coordinates of the model, the Cs 3 Na 9 −A zeolite, were taken from our previous work . In the model, the eight Na atoms are bound to the 6-rings, the three Cs atoms are bound to the 8-ring windows, and the extra Na is located at the center of the β-cage.…”

“… a The parameters were determined with fixed cation charge, δ Na(or Cs) = +0.625 e . ε is in kcal/mol, δ in e, σ in Å, and α in Å 3 . σ O,Na,Cs - M = (σ O,Na,Cs + σ M )/2, ε O,Na,Cs - M = (ε O,Na,Cs × ε M ) 1/2 . …”

“…The MC sampling and energy calculation technique was modified in order to save computing time. The atomic point charges and potential functions of zeolites were taken from previous work 1 Potential energy curves V ( r ) plotted at representative grid points (θ,φ)s along r⃗ for (a) Ne and (b) Xe.…”