  Classical novae are potential sources of gamma-rays, like the 1.275 MeV gamma
emission following 22Na beta decay, that could be detected by appropriate
instruments on board of future satellites like INTEGRAL. It has been shown that
the production of 22Na by novae is affected by the uncertainty on the
21Na(p,gamma)22Mg rate and in particular by the unknown partial widths of the
Ex = 5.714 MeV, J^pi = 2^+, 22Mg level. To reduce these uncertainties, we
performed shell model calculations with the OXBASH code, compared the results
with available spectroscopic data and calculated the missing partial widths.
Finally, we discuss the influence of these results on the 21Na(p,gamma)22Mg
reaction rate and 22Na synthesis.
