Momentum distribution, vibrational dynamics, and the potential of mean force in ice

Lin Lin, Joseph A. Morrone, Roberto Car, Michele Parrinello

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


By analyzing the momentum distribution obtained from path integral and phonon calculations we find that the protons in hexagonal ice experience an anisotropic quasiharmonic effective potential with three distinct principal frequencies that reflect molecular orientation. Due to the importance of anisotropy, anharmonic features of the environment cannot be extracted from existing experimental distributions that involve the spherical average. The full directional distribution is required, and we give a theoretical prediction for this quantity that could be verified in future experiments. Within the quasiharmonic context, anharmonicity in the ground-state dynamics of the proton is substantial and has quantal origin, a finding that impacts the interpretation of several spectroscopies.

Original languageEnglish (US)
Article number220302
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number22
StatePublished - Jun 10 2011

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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