Lebon et al. [Phys. Rev. E 51, 4537 (1995)] have shown that the depolarized light scattering susceptibility spectrum of ZnCl2 at each temperature is well represented by the sum of contributions from the a process, the boson peak, and the microscopic peak. In this Comment, we point out that the fast a process of the coupling model of relaxation makes a very weak contribution to the susceptibility in nonfragile glass formers, such as ZnCl2. Consequently, the coupling model prediction for the fast dynamics in ZnCl2 is essentially the same as the approach of Lebon et al.
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