Enthalpies of vaporization require a pure liquid simulation, as described in Section 2.3.1, as well as a gas phase simulation. This gas phase simulation is performed for a single molecule in the NVT ensemble, with periodic boundaries disabled, using the same Langevin integrator as used with the liquid simulations. These simulations are run for 30 ns instead of the liquid phase 2 ns to converge statistics with only a single molecule. Enthalpies are calculated using Equation 1.