Investigation of the intermediate- and high-density forms of amorphous ice by molecular dynamics calculations and diffraction experiments
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, S7N 5E2 (Canada)
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario, K1A 0R6 (Canada)
- Argonne National Laboratory, Argonne, Illinois 60439 (United States)
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States)
The lack of an 'isosbestic' point in the oxygen-oxygen atom radial distribution functions (RDFs) for the HDA{yields}LDA ice transformation at ambient pressure derived from molecular dynamics (MD) calculations show unequivocally that intermediate phases are not equilibrium mixtures of these two amorphous forms. This is supported by x-ray structure factor data, where it is found that linear combinations of the starting and end amorphous forms do not describe intermediate forms of amorphous ice formed during the transformation. This reflects the fact that the x-ray data are heavily weighted to O-O correlations and therefore sensitive to the basic structural changes that occur during the relaxation process. The ice Ih{yields}HDA transformation is also reexamined using MD to identify its thermodynamic nature. This apparently first-order transition induced by a mechanical instability is investigated by compression followed by decompression to negative pressures. In this study we demonstrated that the full van der Waals loop for this transition can be identified.
- OSTI ID:
- 20719032
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 71, Issue 21; Other Information: DOI: 10.1103/PhysRevB.71.214107; (c) 2005 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AMORPHOUS STATE
COMPRESSIBILITY
COMPRESSION
CORRELATIONS
DENSITY
DIFFRACTION
EQUILIBRIUM
ICE
INSTABILITY
MIXTURES
MOLECULAR DYNAMICS METHOD
OXYGEN
PHASE TRANSFORMATIONS
RELAXATION
SPATIAL DISTRIBUTION
STRUCTURE FACTORS
VAN DER WAALS FORCES
X RADIATION