VIBRATIONS AND FORCE CONSTANTS OF THE HEXAGONAL LITHIUM IODATE CRYSTAL

Force constants of the α-LiIO3 crystal are calculated based on the thirteen k = 0 infrared and Raman active vibrations. Setting up a generalized valence force field for the IO3 group and both valence and central forces for the external interactions has allowed us to obtain good agreement between experimental and calculated frequencies. The introduction of translational and librational coordinates related to the normal coordinate analysis leads to a precise assignment of the frequencies and shows that the degenerate bending vibrations of the IO3 groups are strongly coupled with the translational vibrations of the lithium atoms. © 1979 American Institute of Physics.