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|Type:||Artigo de evento|
|Title:||Sensitivity To Guest-host Force Fields In Adsorption Equilibrium Of Cyclic Hydrocarbons In One-dimensional Molecular Sieve|
Cavalcante Jr. C.L.
|Abstract:||We have investigated the effect of different guest-host force fields (united atom, UA; all-atom, AA; and anisotropic united atom, AUA) on the adsorption of cyclic hydrocarbon molecules in AlPO4-5 molecular sieve. Grand canonical Monte Carlo (GCMC) simulations of benzene, xylene and cyclohexane adsorption and positioning are carried out. The results suggest that the force field choice affects considerably the positioning of benzene and cyclohexane molecules while xylenes presented a smaller sensibility. The force fields difference of sensibilities among cyclical molecules seems to be associated with the critical geometric condition identified by Yashonath and Santikary denominated levitation effect. In this condition, the net forces on the guest due to the host is at a minimum, the levitation ratio () is close to unity and we have a weakly bound guest that can be easily moved from its balance position. Unlike xylene, that is only slightly affected by the choice of the force field, benzene and cyclohexane molecules in AlPO4-5 have such dimensions that result in levitation ratio () close to unity. These results point out to the care that should be taken in the choice of the force field when the guest-host size ratio is near the value defined for the levitation effect.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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