Electric Field Effects on the Intermolecular Interactions in Water Whiskers: Insight from Structures, Energetics, and Properties

Abstract

Modulation of intermolecular interactions in response to external electric fields could be fundamental to the formation of unusual forms of water, such as water whiskers. However, a detailed understanding of the nature of intermolecular interactions in such systems is lacking. In this paper, we present novel theoretical results based on electron correlation calculations regarding the nature of H-bonds in water whiskers, which is revealed by studying their evolution under external electric fields with various field strengths. We find that the water whiskers consisting of 2-7 water molecules all have a chain-length dependent critical electric field. Under the critical electric field, the most compact chain structures are obtained, featuring very strong H-bonds, herein referred to as covalent H-bonds. In the case of a water dimer whisker, the bond length of the novel covalent H-bond shortens by 25%, the covalent bond order increases by 9 times, and accordingly the H-bond energy is strengthened by 5 times compared to the normal H-bond in a (H2O)2 cluster. Below the critical electric field, it is observed that, with increasing field strength, H-bonding orbitals display gradual evolutions in the orbital energy, orbital ordering, and orbital nature (i.e., from typical π-style orbital to unusual σ-style double H-bonding orbital). We also show that, beyond the critical electric field, a single water whisker may disintegrate to form a loosely bound zwitterionic chain due to a relay-style proton transfer, whereas two water whiskers may undergo intermolecular cross-linking to form a quasi-two-dimensional water network. Overall, these results help shed new insight on the effects of electric fields on water whisker formation.

An External Electric Field Manipulated Second-Order Nonlinear Optical Switch of an Electride Molecule: A Long-Range Electron Transfer Forms a Lone Excess Electron Pair and Quenches Singlet Diradical

“…From electric field effects on the hydrogen bonding evolution in water whiskers, 98 it is quite interesting that, with increasing external field strength, molecular orbitals can evolve in the orbital energy, orbital nature, and orbital order.…”

Electromagnetic bioeffects: a multiscale molecular simulation perspective

“…98 They also noted that the critical external EF needed to induce this bonding decreases monotonically with increasing chain length of the water whiskers. 98 More recently, Lu and co-workers used both DFT and MD to study the formation of water nanowires induced by more modest external EFs (∼3 V nm −1 ). 99 These authors noted that nanowires around 10 nm long are rapidly formed when an external EF is applied and is accelerated by increasing the applied field strength.…”

“…97 Huang and co-workers used wavefunction theory to investigate the effect of very intense static EFs on the structure of water clusters (H 2 O) n , where n = 2–7. 98 These authors characterised the unusually strong H-bonding characteristics of the resulting water whiskers that form when a critical EF (∼10 V nm −1 ) is applied. 98 They also noted that the critical external EF needed to induce this bonding decreases monotonically with increasing chain length of the water whiskers.…”

“…98 These authors characterised the unusually strong H-bonding characteristics of the resulting water whiskers that form when a critical EF (∼10 V nm −1 ) is applied. 98 They also noted that the critical external EF needed to induce this bonding decreases monotonically with increasing chain length of the water whiskers. 98 More recently, Lu and co-workers used both DFT and MD to study the formation of water nanowires induced by more modest external EFs (∼3 V nm −1 ).…”

Experimental Investigations on Electric-Field-Induced Crystallization in Erythritol

“…Depending on its strength, the E-field can also lead to the disruption of the H-bond network and even provoke water dissociation. Despite substantial progress, the mechanism by which the E-field interacts with water remains a widely debated research topic [ 11 ]. However, there is experimental evidence that the application of E-fields between 0.45 V/m and 3 GV/m encourages ice formation in supercooled water and accelerates its crystallization [ 12 , 13 ].…”