Shell-model calculations of stellar weak interaction rates.: I.: Gamow-Teller distributions and spectra of nuclei in the mass range A=45-65

Electron capture and beta-decay rates on nuclei in the mass range A = 45-65 play an important role in many astrophysical environments. The determination of these rates by large-scale shell-model calculations is desirable, but it requires to reproduce the Gamow-Teller strength distributions and spectra of the pf shell nuclei. We show in this paper that large-scale shell-model calculations, employing a slightly monopole-corrected version of the well-known KB3 interaction, fulfill these necessary requirements. In particular, our calculations reproduce the experimentally available GT(+) and GT(-) strength distributions and the nuclear halflives, and describe the nuclear spectra appropriately. (C) 1999 Elsevier Science B.V, All rights reserved.