theory one sees that a large amount of calculations of weak interaction rates for astrophysical applications have become available in recent times (e.g. [@Nabi99; @Heger01; @Langanke01; @Rahman07; @Nabi04]).

![The comparison of pn-QRPA, experimental, and shell model B(GT$_{+}$) strength distribution of $^{57}$Zn as a function of $^{57}$Cu excitation energy.[]{data-label="fig1"}](fig.1.eps){width="3.3in" height="4.3in"}

To allow the reader the judgment of quality achieved in the pn-QRPA model underlying the stellar weak interaction rate calculation, the B(GT) strength calculated using the pn-QRPA theory is compared with experimental [@Jokinen02] and with B(GT) strengths predictions obtained from a large-scale shell model calculation using the effective interaction KB3G [@Poves01]. The results are depicted in Fig. \[fig1\]. Vieira et al. [@Vieira76] for the first time probed the structure of $^{57}$Cu in the beta decay of $^{57}$Zn by employing the $^{40}$Ca($^{20}$Ne, 3n) fusion evaporation reaction and by Zhou et al. [@Zhou96] in the $^{1}$H($^{58}$Ni, $^{57}$Cu-$\gamma $)2n reaction by using the recoil mass spectrometer MARS at the Texas A&M Cyclotron Institute. Considerable improvements were obtained in Ref. [@Jokinen02] concerning the quality of the experimental data, in particular with respect to source purity and proton energy resolution.

![The pn-QRPA calculated integrated strength within the $Q_{EC}$ window. $E_{j}$ represents the energy in daughter nucleus 