On the inadequacy of linear pressure dependence of vibrational frequency

The pressure behaviour of vibrational frequencies was discussed in a recent paper by Liu [Solid State Commun. 114 (2000) 637]. It was found that the a ssumption of a linear pressure dependence is not justified, and it was conc luded that the Murnaghan equation-of-state (EOS) is inadequate for solids. In contrast, here it will be shown that the linear pressure dependence prov ides no difficulties when introduced correctly and that the Murnaghan EOS c an be used consistently. (C) 2000 Elsevier Science Ltd. All rights reserved .