In the theory of the field-ion miscroscope, there are one- and three-dimensional approaches for the JWKB tunneling rate-constant. If I remember correctly, its energy dependence differs between the two approaches. See, e.g.,

Surface Science 277 (1992)173-183

Field-ion microscope tunnelling calculations for the aluminium (111)

and (110) surfaces

S.C. Lam and R.J. Needs

Cavendish Laboratory, University of Cambridge,

http://ac.els-cdn.com/003960289290622D/1-s2.0-003960289290622D-main.pdf?_tid=faa949ba-2ab6-11e3-91c2-00000aab0f6c&acdnat=1380645293_e20ec94848283eea951825cdada5de9e

and references therein.