TIP4P potentials, potential energy surfaces

Figure 3 Above Radial distribution functions for water samples at 25 C using the TIP4P potential (solid line) and the TIP4P potential plus a localized repulsive barrier (dashed line), as discussed in the text. Below Constant potential surfaces of the localized repulsion added to the TIP4P model. The surfaces correspond to an energy value of 1 kT.

We first considered the water hexamer, which is the smallest cluster for which a noncyclic structure is found to be the global minimum, both theoretically [318-321] and experimentally [322]. For the TIP4P potential we have probably located the majority of the minima and transition states on the PES, while for ASP-W4 there are many more stationary points, and our sampling of the higher energy region of the surface is incomplete. For TIP4P... 

The minimum potential energy curve of the water dimer is given in Figure 6 for three different water models. Two are effective models, and one is a nonempirical model for comparison. The nonempirical molecular orbital (NEMO) " surface mimics the true two-body water potential V2 in Eq. [44]. It is rather flat, and its minimum is not as sharply defined as in the effective potentials. Pairwise additive potentials like and TIP4P ° show their... 

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