Lattice dynamics of crystals of the calcite structure. I. Normal frequencies and normal modes at zero wave vector

✍ Scribed by M. Plihal; G. Schaack

• Publisher: John Wiley and Sons
• Year: 1970
• Tongue: English
• Weight: 620 KB
• Volume: 42
• Category: Article
• ISSN: 0370-1972
• DOI: 10.1002/pssb.19700420203

✦ Synopsis

Abstract

Normal frequencies and normal modes of the lattice vibrations for the wave vector |y| = 0 have been calculated for the isomorphic series of NaNO~3~, CaCO~3~, and MgCO~3~. The calculated frequencies of the infrared‐ and Raman‐active modes have been fitted to the experimentally known values for T = 300 °K by variation of the coupling constants. Three different models have been used: a) In model 1 only the short‐range interactions by central forces have been taken into account. b) In model 2 the Coulomb‐interaction has been included (rigid‐ion model). c) In model 3 the anisotropic polarizability of the anion has been considered in addition (shell model). The best fit has been obtained with the shell‐model. The calculated frequencies and eigen‐vectors are given and discussed in comparison with experimental results.