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Article
Density‐functional theory for the solid alkali cyanides
Journal of Chemical Physics (1982)
  • Richard Alan Lesar, Harvard University
  • R. G. Gordon, Harvard University
Abstract
Structural properties of the solid alkali cyanides were studied with a recently reported a b i n i t i otheory based on the Gordon–Kim electron gas model. The low temperature crystal structures of LiCN, NaCN, KCN, RbCN, and CsCN were examined. The average error in lattice parameters is 2.6% and in lattice dissociation energy 1.7%. For the NaCN and KCN systems, the energy differences between the ferroelectric and antiferroelectricstructures were examined and the antiferroelectricstructure was found to be more stable at zero temperature by about 0.5–0.8 kcal/mol. The high pressure phases of KCN were studied and the phase diagram partially mapped out at 0 K. The crystal structure of RbCN at low temperatures was studied, and the orthorhombic P m m nstructure found to be more stable than the monoclinic A astructure. The heat of formation of RbCN was calculated at 0 K to be about 31.4±7 kcal/mol. The cyanide electron density was found to shift from the C atom towards the N atom in all crystals studied, when the free space CN− ion is incorporated into a crystal.
Keywords
  • crystal structures,
  • antiferroelectricity,
  • dissociation energies,
  • electron gas,
  • formation enthalpy
Publication Date
October 1, 1982
Publisher Statement
Copyright 1982 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.
Citation Information
Richard Alan Lesar and R. G. Gordon. "Density‐functional theory for the solid alkali cyanides" Journal of Chemical Physics Vol. 77 Iss. 7 (1982)
Available at: http://works.bepress.com/richard_lesar/39/