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Molecular dynamics simulation of water liquid is studied using TIP4P model.
The H-bond patterns were analyzed with a Voronoi Polyhedra (VP) construction
of the oxygen atom distributions. An asphericity parameter for VP was used to
characterize the distribution of the local H-bonds. With different asphericity
values, there exist the isosbestic points in the O-O radial
distribution function
in NVE ensemble. The spatial distribution function shows the
tetrahedarl site and
interstitial site distributed with distinct ratio whiling h
changed. A heterogeneous
bimodal distribution of local hydrogen bond patterns implies a
fluctuation between
high-density water and low-density water during supercooled. A
bi-exponential decay
of the dipolar autocorrelation function is associated with locally cooperative
rotation around the H-bond axis and with rototranslational
coupling motion of the
water molecule in a disordered cage. It suggests liquid water can be viewed a
dynamical mixture of two types of local H-bond structures.
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