Comment on “Periodic wave functions and number of extended states in random dimer systems”

In a recent report, Huang, Wu, and Gong [Phys. Rev. B 55, 11 018 (1997)] studied numerically the electronic properties of a random dimer model (RDM) and found extended periodic wave functions near the critical energies. We argue that there are no periodic wave functions in the RDM but close to the critical energies there exist periodic envelopes. These envelopes are given by the nondisordered properties of the system.