  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
