Comment on: “Zero-temperature conductance of parallel T-shape double quantum dots” [Physica E 39 (2007) 214]

In a recent paper [Physica E 39 (2007) 214, arXiv:0708.1842v1] Crisan, Grosu, and Tifrea revisited the problem of the conductance through a double-quantum-dot molecule connected to electrodes in a T-shape configuration. The authors obtained an expression for the conductance that disagrees with previous results in the literature. We point out an error in their derivation of the conductance formula and show that it gives unphysical results even for non-interacting quantum dots.