Fixed-charge models

Whitfield TW, Varma S, Harder E, Lamoureux G, Rempe SB, Roux B (2007) Theoretical study of aqueous solvation of K+ comparing ab initio, polarizable, and fixed-charge models. J Chem Theory Comput 3(6) 2068-2082... 

We finish the discussion of force fields developed for imidazolium-based systems by describing the work of Voth and co-workers who simulated [C2mim][N03] first with traditional fixed-charge models and then with a model that included electronic polarizability. For the fixed-charge system, Del Popolo and Voth used a force field having the AMBER function form, with parameters for the cation and anion taken from existing sources. They... 

Table 7 Parameters Used in Rigid, Fixed-Charge Models...

T. W. Whitfield, S. Varma, E. Harder, G. Lamoureux, S. B. Rempe, and B. Roux,/. Cbem. Theory Comput., 3(6), 2068-2082 (2007). Theoretical Study of Aqueous Solvation of K(+) Comparing Ab Initio, Polarizable, and Fixed-Charge Models. 

Bhargava and Balasubramanian[142] carried out equilibrium MD simulations with a fixed charge model of 1,3-dimethylimidazolium chloride ([mmim][Cl]) at 425 K. Using a Green-Kubo expression (that is, the long-time integral of the stress-stress time correlation function) they obtained a viscosity for [mmim][Cl] that was about four times higher than the experimental value for [emim][Cl]. Apparently, there were no experimental data at this temperature for [mmim][Cl], but the authors assumed that the values would be similar to [emim][Cl]. 

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