Ab initio spectroscopy of water under electric fields

Area of Science:

• Physical Chemistry
• Spectroscopy
• Computational Chemistry

Background:

• Extensive literature exists on water spectroscopy under various conditions.
• However, infrared (IR) and Raman spectra of water under electric fields remain under-investigated.

Purpose of the Study:

• To investigate the effects of static electric fields on the IR and Raman spectra of bulk liquid water.
• To analyze field-induced changes in water's molecular structure and hydrogen bonding network.

Main Methods:

• Ab initio molecular dynamics simulations were employed.
• IR and Raman spectra were calculated for liquid water subjected to varying static electric field intensities.

Main Results:

• A contraction of the frequency range was observed in both IR and Raman spectra with increasing field intensity.
• The OH stretching band shifted to lower frequencies, indicating strengthened hydrogen bonds.
• Other spectral bands were up-shifted, and the librational mode band showed significant modification.
• Water's orientational tetrahedral order increased, leading to a more ice-like structure.

Conclusions:

• Static electric fields significantly alter the spectral properties of liquid water.
• The electric field strengthens the hydrogen bond network and induces a more ordered, ice-like structure in water.
• This study provides novel insights into the behavior of water under external electric fields.