  Mathematical structure of the reflection coefficients for the one-dimensional
Fokker-Planck equation is studied. A new formalism using differential operators
is introduced and applied to the analysis in high- and low-energy regions.
Formulas for high-energy and low-energy expansions are derived, and expressions
for the coefficients of the expansion, as well as the remainder terms, are
obtained for general forms of the potential. Conditions for the validity of
these expansions are discussed on the basis of the analysis of the remainder
terms.
