  Coulomb excitation is a standard method used to extract quadrupole excitation
strengths of even-even nuclei. In typical analyses the reaction is assumed to
be one-step, Coulomb only, and is treated within a semi-classical model. In
this work, fully-quantal coupled-channel calculations are performed for three
test cases in order to determine the importance of multi-step effects, nuclear
contributions, feeding from other states and corrections to the semi-classical
approximation. We study the excitation of 30S, 58Ni and 78Kr on 197Au at ~ 50
AMeV. We find that nuclear effects may contribute more than 10% and that
feeding contributions can be larger than 15%. These corrections do not alter
significantly the published B(E2) values, however an additional theoretical
error of up to 13% should be added to the experimental uncertainty if the
semi-classical model is used. This theoretical error is reduced to less than 7%
when performing a quantal coupled-channel analysis.
