We use a new representation for the semiclassical Green's function of the D
irac equation in the Coulomb field to find an exact (in the parameter Z alp
ha) expression for the amplitudes of small-angle Delbruck scattering of hig
h-energy photons. The values of these amplitudes agree with those obtained
in earlier calculations, but the structure of the expressions is much simpl
er than that of previously known representations, which makes numerical cal
culations much easier. (C) 1999 American Institute of Physics. [S1063-7761(
99)00807-0].