Energetics competition in centrally four-coordinated water clusters and Raman spectroscopic signature for hydrogen bonding

Abstract

Extending the electronic structure of four-coordinated hydrogen bonds (H-bonds) to medium sized water cages (H₂O)_n (n = 17, 19, 20, 21, 23 and 25), we separate the H-bonded neighbour molecules of their centrally four-coordinated water (C4CW) molecules from other molecules in outer cages and discover these two regions interact competitively with the central molecule, showing complementary interaction energy curves with respect to size changes. Raman spectral analyses clearly reveal the characteristic vibration response of water molecules to different H-bonding environment, where the C4CW structure is relatively sensitive. Our theoretical research advances a new perspective for the study of H-bonding interaction in liquid water.