The production of electron-positron pairs with the capture of the electron in
an atomic orbital is investigated for the conditions of the Relativistic Heavy
Ion Collider (RHIC) and the Large Hadron Collider LHC). Dirac wave functions
for the leptons are used, taking corrections to orders of Z.alpha into account.
The dependence on the transverse momentum transfer is studied and the accuracy
of the equivalent photon approximation is discussed as a function of the
nuclear charge.Comment: 4 postscript figure
