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. Author manuscript; available in PMC: 2016 Feb 16.
Published in final edited form as: J Phys Chem B. 2008 Feb 27;112(11):3509–3521. doi: 10.1021/jp709729d

Figure 3.

Figure 3

The enthalpy of vaporization and molecular volume of neat liquid simulations for the four electrostatic models studied. Also included is the nonpolarizable CHARMM model. The simulations were run at T = 373 K. Each electrostatic model corresponds to a color. The individual circles of each electrostatic model type correspond to a different choice of LJ parameters. Each model gives interaction energies and geometries that agree to within 0.5 kcal/mol and 0.15 Å of QM calculations for the NMA–water dimer optimizations illustrated in Figure 2. The enthalpy of vaporization is calculated from the average change in energy upon formation of the dense system, ΔHvap = kT – (〈u〉liq - 〈u〉gas). Models that lie within 0.5 Å3 of the experimental molar volume (black box) were chosen for the next stage of the parametrization. Two estimates for the experimental enthalpy are illustrated.77,78