Effect of static electric fields on liquid water, its structure, dynamics, and hydrogen bond asymmetry: A molecular dynamics simulation study of TIP4P/2005 water model

We study the effect of static electric fields of 0.1, 0.4, and 1.0 V/nm on the hydrogen bond structure and dynamics of TIP4P/2005 water at 1 bar and at temperatures between 300 and 200 K using molecular dynamics simulations. At all these temperatures, simulating liquid water with electric fields of 0.1 and 0.4 V/nm has no additional effect on its structural and dynamical changes, which otherwise already take place due to cooling. However, the introduction of 1.0 V/nm field enhances the slowing down of liquid water dynamics, crystallizes it to cubic ice at 240 and 220 K, and amorphizes it at 200 K. At 240 and 220 K, crystallization occurs within 5 and 50 ns, respectively. An electric field of 1 V/nm increases the relaxation times in addition to what cooling does. We note that when liquid water's metastability limit is reached, crystallization is averted and amorphization takes place. Both equilibrium (liquid-solid) and non-equilibrium (liquid-amorphous) transformations are observed at 1 V/nm. Moreover, with an increase in the electric field, H-bonds become stronger. However, the donor-acceptor asymmetry (the difference between the strengths of two donor/acceptor bonds) remains even when crystallization or amorphization takes place. At low temperatures, increasing electric fields on liquid water increases both its crystallization and amorphization tendencies.

Automated summary

We studied the effect of static electric fields on the hydrogen bond structure and dynamics of TIP4P/2005 water. Electric fields of 0.1 and 0.4 V/nm had no additional effect on the water's changes, while a field of 1.0 V/nm enhanced the slowing down of dynamics and caused crystallization or amorphization. With increased electric fields, H-bonds became stronger, but the asymmetry between donor/acceptor bonds remained.