Comment on "Charge-parity symmetry observed through Friedel oscillations in chiral charge-density waves" by J. Ishioka et al

In their publication [Phys. Rev B, 84, 245125 (2011)], Ishioka et al. discuss the recently discovered chiral charge density wave state in 1T-TiSe2 in terms of a parameter H_CDW, whose sign is suggested to correspond to the handedness of the chiral order. Here we point out that H_CDW, as defined by Ishioka et al., cannot be used to characterize chirality in that way. An alternative measure of chirality for the specific case of 1T-TiSe2 is suggested.