Simulations of H₂O Solid, Liquid, and Clusters, with an Emphasis on Ferroelectric Ordering Transition in Hexagonal Ice

Abstract

Simulations are presented of H2O ice, liquid, and clusters (H2O) n n ≤ 7. The first part is devoted to orientational energetics of ice. Ordinary hexagonal ice is orientationally disordered; a transition to an ordered form (ice XI) can be induced at 72 K. The recently demonstrated ferroelectric structure of ice XI (Jackson, S. M.; Wield, V. M.; Whitworth, R. W.; Oguro, M.; Wilson, C. J. Phys. Chem. B 1997, 101, 6142) seems to contradict our understanding of H2O···H2O interactions. A polarizable water potential is proposed that accounts qualitatively for the existence of ferroelectric ice XI; its crucial ingredient is the location of the polarizability center. This potential is then tested in classical trajectory simulations of water structure, energetics, self-diffusion, and dielectric constant. Cluster energetics and rotational constants are calculated using the rigid body diffusion Monte Carlo technique.

Evolution of the structure of amorphous ice: From low-density amorphous through high-density amorphous to very high-density amorphous ice

“…An initial proton-disordered configuration of I h ice with 360 H 2 O molecules and zero dipole moment in an orthorhombic box was prepared using the Monte Carlo procedure of Ref. 36 . The interaction between water molecules was described by the classical TIP4P model 37 .…”

Structure, spectra, and mobility of low‐pressure ices: Ice I, amorphous solid water, and clathrate hydrates at T < 150 K

“…Here a limited set of advances, with possible applicability to space science but not noted in the previous sections, is considered. Recently, a polarizable potential was developed with the specific property that it reflects the lower energy of ordered ice XI [Buch et al, 1998]; a property not found with the earlier analytical potentials. The analytical potentials permit detailed studies of large numbers of water molecules in protondisordered ice configurations and have been applied to questions such as the existence of the liquid-like layer at the ice surface near the melting point, the structure of ultrathin films on metal surfaces [Witek and Buch, 1999] and large clusters at much lower temperatures, and the nature of the orientational defects in ice [Podeszwa and Buch, 1999].…”

Importance sampling in rigid body diffusion Monte Carlo

“…A convenient Gaussian short-time approximation for such monomer rotational motion was assumed in that work. A number of applications of RBDMC have since been carried out, all of which use a combination of this angular sampling for monomer rotation in local monomer principal axis frames, together with the conventional sampling of translational motions of monomers in the laboratory frame [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. The rigid body rotations are carried out using either Euler angles, or quaternion algebra [16].…”