Comment on “Tip-to-surface distance variations vs voltage in scanning tunneling microscopy”

Notational, geometrical, and electrical inconsistencies in the electrostatic potential described in a recent paper [G. Seine et al., Phys. Rev. B 60, 11 045 (1999)] are pointed out and removed where possible. The prolate spheroidal harmonic expansion of the image potential for confocal hyperboloidal electrodes is also given.