Comment on "Characterization of the tunneling conductance across DNA bases"

In a recent paper, Zikic et al. [Phys. Rev. E 74, 011919 (2006)] present first-principles calculations of the DNA nucleotides' electrical conductance. They report qualitative and quantitative differences with previous work, in particular with that of Zwolak and Di Ventra [Nano Lett. 5, 421 (2005)] and Lagerqvist et al. [Nano Lett. 6, 779 (2006)]. In this comment we address the alleged discrepancies, showing that they come from a misrepresentation of our research. Further, we discuss in more detail the issue of geometric fluctuations previously investigated by us, and raised again in the work of Zikic et al. In addition, we point out erroneous comments made by Zikic et al. regarding the use of density functional theory calculations in transport.