(517e) Improved Conformational Sampling for Reaction Ensemble Monte Carlo Simulations

In many industrial applications it is imperative to understand the reaction behavior of various chemical mixtures. While comprehensive knowledge may be limited by experimental techniques, molecular simulation provides unique complementary insight into reacting systems. Smith et al.1 and Johnson et al.2 independently developed a methodology capable of predicting equilibrium concentrations of reacting species, referred to as reaction ensemble Monte Carlo (RxMC). Yet, as in other Monte Carlo implementations, RxMC can suffer from inefficient sampling for systems of high density and/or high complexity. We introduce the continuous fractional component3 (CFC) method within the RxMC framework which overcomes sampling difficulties by allowing for gradual introduction and subtraction of products and reactants. We apply this method to study the synthesis of gasoline additive methyl-tert-butyl-ether(MTBE) from isobutene and methanol. This presentation will describe how to implement CFC to model simultaneous vapor-liquid and chemical equilibrium as well as demonstrate enhanced efficiency in calculation of equilibrium concentrations.

1 Smith, W.R., Triska, B., J. Chem. Phys. 1994, 100, 3019-3027

2 Johnson, J.K., Panagiotopoulos, A.Z., Gubbins, K.E., Mol. Phys. 1994, 81, 717-733

3 Shi, W., Maginn, E.J., J. Chem. Theory Comput. 2007, 3, 1451-1463