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Molecular dynamics studies of lattice vibrations of proton-ordered ice XI
Computer Physics Communications Computer Physics Communications121-122 (1999) 666 www.elsevier.nl/locate/cpc
Abstract
Molecular dynamics studies of lattice vibrations of proton-ordered ice XI H. Itoh 1, K. Kawamura Department of Earth and Planetary Sciences, Faculty of Science, Tol,3,oInstitute of Technology, 2-12-10okayama, Meguro, Tokyo 152-8551, Japan
Molecular dynamics simulations of ice XI, the proton-ordered phase of hexagonal ice Ih, have been performed using the KKY potential model [1] which allows unconstrained atomic motions. Dynamical properties of ice XI are still uncertain because the phase transition from ice Ih to XI occurs by doping KOH and it is difficult to prepare a single crystal of pure H20. In the previous simulations [2,3] vibrational spectra of ice XI unknown in experiments were calculated in detail from the Fourier transform of the velocity autocorrelation functions. A remarkable difference between the spectra of ice Ih and ice XI was found in the librational band, which consists of four major peaks in ice XI; ice lh is well known to have a broad librational band. In the present study the four peaks were directly assigned to the three librational modes for a water molecule from the trajectories of the protons obtained by molecular dynamics simulations. Moreover the polarized vibrational spectrum was calculated in order to clarify the anisotropic dynamics of water molecules in ice XI affected by the ferroelectric structure Cmc21. © 1999 Elsevier Science B.V. All rights reserved.
References [1] N. Kumagai,K. Kawamura,T. Yokokawa, Mol. Sim. 12 (1994) 177. [2] H. Itoh, K. Kawamura,T. Hondoh, S. Mae, PhysicaB 219/220 (1996) 469. [3] H. Itoh, K. Kawamura,T. Hondoh, S. Mac, J. Chem. Phys. (in press).
I E-mail:[email protected]. 0010-4655/99/$ - see front matter © 1999 ElsevierScience B.V. All rights reserved.
Abstract
Molecular dynamics studies of lattice vibrations of proton-ordered ice XI H. Itoh 1, K. Kawamura Department of Earth and Planetary Sciences, Faculty of Science, Tol,3,oInstitute of Technology, 2-12-10okayama, Meguro, Tokyo 152-8551, Japan
Molecular dynamics simulations of ice XI, the proton-ordered phase of hexagonal ice Ih, have been performed using the KKY potential model [1] which allows unconstrained atomic motions. Dynamical properties of ice XI are still uncertain because the phase transition from ice Ih to XI occurs by doping KOH and it is difficult to prepare a single crystal of pure H20. In the previous simulations [2,3] vibrational spectra of ice XI unknown in experiments were calculated in detail from the Fourier transform of the velocity autocorrelation functions. A remarkable difference between the spectra of ice Ih and ice XI was found in the librational band, which consists of four major peaks in ice XI; ice lh is well known to have a broad librational band. In the present study the four peaks were directly assigned to the three librational modes for a water molecule from the trajectories of the protons obtained by molecular dynamics simulations. Moreover the polarized vibrational spectrum was calculated in order to clarify the anisotropic dynamics of water molecules in ice XI affected by the ferroelectric structure Cmc21. © 1999 Elsevier Science B.V. All rights reserved.
References [1] N. Kumagai,K. Kawamura,T. Yokokawa, Mol. Sim. 12 (1994) 177. [2] H. Itoh, K. Kawamura,T. Hondoh, S. Mae, PhysicaB 219/220 (1996) 469. [3] H. Itoh, K. Kawamura,T. Hondoh, S. Mac, J. Chem. Phys. (in press).
I E-mail:[email protected]. 0010-4655/99/$ - see front matter © 1999 ElsevierScience B.V. All rights reserved.