Revised 4‑Point\nWater Model for the Classical\nDrude Oscillator Polarizable Force Field: SWM4-HLJ

In this work the 4-point polarizable SWM4 Drude water\nmodel is\nreparametrized. Multiple models were developed using different strategies\ntoward reproduction of specific target data. Results indicate that\nno individual model can reproduce all the selected target data in\nthe context of the present form of the potential energy function.\nThe changes considered in the new models include, 1) variations in\nthe gas phase dipole moment, 2) variations in the molecular polarizability,\n3) variations of the distance between the oxygen and the M site, 4)\nvariation of the oxygen Lennard-Jones (LJ) parameters, 5) introduction\nof a LJ potential to the hydrogen atoms, and 6) variations of the\nH–O–H angle. Detailed analysis is presented for 3 new\nwater models from which a final model, SWM4-HLJ, is selected as the\nfuture default model for the Drude polarizable force field. The model\nmaintains the gas phase dipole moment as the experimental value while\nthe remaining listed terms were adjusted including a larger H–O–H\nangle (108.12). Compared to its predecessor, SWM4-NDP, the self-diffusion\ncoefficient, water dimer properties, and water cluster energies are\ngreatly improved. The temperature dependence of the density of the\nnew model also performs better. Overall, the new SWM4-HLJ water model\nis a general improvement and a good balance between microscopic and\nbulk properties is achieved.