  A simple integral representation is derived for the quasiclassical Green
function of the Dirac equation in an arbitrary spherically-symmetric decreasing
external field. The consideration is based on the use of the quasiclassical
radial wave functions with the main contribution of large angular momenta taken
into account. The Green function obtained is applied to the calculation of the
Delbruck scattering amplitudes in a screened Coulomb field.
