Are there Helium-like Protonic States of Individual Water Molecules in Liquid H2O?

TL;DR

This paper explores the possibility that individual water molecules in liquid water can adopt helium-like protonic states, indicating a potential coexistence of bent and spherical molecular configurations due to confinement effects.

Contribution

It introduces a theoretical model showing how confinement can induce helium-like states in water molecules, suggesting a new perspective on liquid water's molecular structure.

Findings

Helium-like protonic states can thermally coexist with bent states at specific confinement strengths.

A maximum entropy estimate characterizes the angular correlation in helium-like states.

The model predicts structural coexistence in liquid water based on confinement effects.

Abstract

Are there indications that individual H2O molecules in liquid water can loose their bent structure, i.e. that the protons give up their rigid angular correlation and behave largely uncorrelated, similar to electrons in the ground-state of helium? In agreement with the two-state picture of liquid water this would allow for the thermal coexistence of tetraedrically coordinated and spherical water molecules in the liquid. In the Hooke-Calogero model of a confined triatomic of XY2-type it is shown that energetically low-lying zero orbital-momentum states, which are bent if unconfined can change to helium-like shape under increasing confinement strength f. For the respective states this occurs at different values for f. It turns out that at f = 2.79 a bent and a helium-like state can thermally coexist. In order to characterize more precisely 'helium-like' angular correlation a maximum entropy estimate for the marginal correlation of electrons in the helium ground state is given. KEY WORDS: Liquid water, molecular structure, noble gases, confinement, two-state theories, non-Born-Oppenheimer wave functions