Karabulut, IAtav, USafak, H2020-03-262020-03-2620052469-99502469-9969https://dx.doi.org/10.1103/PhysRevB.72.207301https://hdl.handle.net/20.500.12395/19631Zhang and Xie [Phys. Rev. B 68, 235315 (2003)] presented their results for the second harmonic generation (SHG) susceptibility in electric-field-biased parabolic and semiparabolic quantum wells (QW's). In this Comment, we demonstrate that the results presented for the SHG coefficient in a parabolic QW with an applied electric field are not physically sound and they contradict with well-established properties of the Hermite polynomials which just happen to be the wave functions describing such a system. It is shown that in a parabolic QW with an applied electric field intersubband transitions contribute to neither second nor any higher order harmonic generation.en10.1103/PhysRevB.72.207301info:eu-repo/semantics/openAccessEditorial7220Q1WOS:000233603900138Q1