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Lattice dynamics of crystals of the calcite structure. I. Normal frequencies and normal modes at zero wave vector
Author(s) -
Plihal M.,
Schaack G.
Publication year - 1970
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19700420203
Subject(s) - normal mode , polarizability , anisotropy , shell model , lattice (music) , molecular physics , ion , physics , coulomb , chemistry , wave vector , vibration , condensed matter physics , atomic physics , quantum mechanics , molecule , acoustics , electron
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.