Landau's approach to symmetry changes inA15(Oh3−Pm3n) structure

It is found that the results of Jarić and Birman of possible lower-symmetry phases arising from the $A15\mathrm{}$ structure are not correct and, by using the Landau approach to symmetry changes at continuous phase transitions the corrected results for symmetry changes at ${}_{}{}^{*}{}_{}{}^{}\overrightarrow{\mathrm{X}}$ and ${}_{}{}^{*}{}_{}{}^{}\overrightarrow{\mathrm{R}}$ points of the Brillouin zone are presented.