Abstract
This paper makes two brief points about an earlier paper by Cracknell (abstr. A34131 of 1973). One is to identify the group-theoretical labels for the acoustic-mode phonons along Delta , Sigma , and Lambda in FeF2 in terms of the more traditional LA (longitudinal acoustic) and TA (transverse acoustic) labels. The second is to correct an error in the labels given previously to the phonon symmetries along Delta ; this resulted from an error that previously was not noticed in one of the tables in a paper by Dimmock and Wheeler (1962).