| Popis: |
Comments are given on different representations of the force fields for LiBeF 3 and Li 2 BeF 4 . For both structures a planar bridged C 2v model has been adopted. A representation ( F ) in terms of symmetry coordinates is obtained by a transformation of a force-constant matrix, F , which is based on valence coordinates with redundancies. Algebraical and numerical expressions for the connection between these two kinds of force constants are derived in the cases of species A 1 and B 2 for the LiBeF 3 model and A 1 for Li 2 BeF 4 . In the latter case the influence of structural parameters on the relations in question was found to be substantial. |
