  We report here the microscopic calculation of weak interaction rates in
stellar matter for 709 nuclei with A = 18 to 100 using a generalized form of
proton-neutron quasiparticle RPA model with separable Gamow-Teller forces. This
is the first ever extensive microscopic calculation of weak rates calculated
over a wide temperature-density grid which includes 10^7 \leq T(K) \leq 30
\times 10^9 and 10 \leq \rho Y_{e} (gcm^{-3}) \leq 10^{11}, and over a larger
mass range. Particle emission processes from excited states, previously
ignored, are taken into account, and are found to significantly affect some
$\beta$ decay rates. The calculated capture and decay rates take into
consideration the latest experimental energy levels and $ft$ value
compilations. Our calculation of electron capture and $\beta$-decay rates, in
the $fp$-shell, show considerable differences with a recently reported shell
model diagonalization approach calculation.
