High-pressure behavior of solid F/sub 2/ at low temperatures
The equilibrium structures, orientations, and molar volume of solid F/sub 2/ at zero temperature are calculated at pressures 0 less than or equal to P less than or equal to 100 kbar, by minimizing the Gibbs free energy of a general monoclinic lattice with two molecules per unit cell. This was accomplished with the Fletcher quasi-Newton method, which varies all the independent degrees of freedom until the force on each atom is eliminated. The resulting structures are C2/c, and no evidence of a phase transition is found, which is consistent with recent experimental data. On the basis of these calculated structures, the pressure dependence of the vibron stretch mode frequency is calculated by assuming that the crystal field of the solid acts as a small perturbation on the gas-phase intramolecular potential, and the k = 0 libron- and phonon-mode frequencies are determined with standard lattice dynamics techniques. These predicted frequencies are compared with results from recent Raman scattering measurements.
- Research Organization:
- Colorado State Univ., Fort Collins
- DOE Contract Number:
- AC02-84ER45050
- OSTI ID:
- 5344051
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 90:19
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
FLUORINE
CRYSTAL STRUCTURE
FREE ENTHALPY
ABSOLUTE ZERO TEMPERATURE
BOND ANGLE
BOND LENGTHS
LATTICE PARAMETERS
LATTICE VIBRATIONS
MONOCLINIC LATTICES
PHONONS
PRESSURE DEPENDENCE
SPACE GROUPS
THEORETICAL DATA
ULTRALOW TEMPERATURE
CRYSTAL LATTICES
DATA
DIMENSIONS
ELEMENTS
ENERGY
HALOGENS
INFORMATION
LENGTH
NONMETALS
NUMERICAL DATA
PHYSICAL PROPERTIES
QUASI PARTICLES
THERMODYNAMIC PROPERTIES
400201* - Chemical & Physicochemical Properties