  Radiative capture of nucleons at energies of astrophysical interest is one of
the most important processes for nucleosynthesis. The nucleon capture can occur
either by a compound nucleus reaction or by a direct process. The compound
reaction cross sections are usually very small, specially for light nuclei. The
direct capture proceeds either via the formation of a single-particle
resonance, or a non-resonant capture process. In this work we calculate
radiative capture cross sections and astrophysical S-factors for nuclei in the
mass region A<20 using single-particle states. We carefully discuss the
parameter fitting procedure adopted in the simplified two-body treatment of the
capture process. Then we produce a detailed list of cases for which the model
works well. Useful quantities, such as spectroscopic factors and asymptotic
normalization coefficients, are obtained and compared to published data.
