  We report calculations of energy levels, radiative rates, and electron impact
excitation rates for transitions in Li-like ions with 12 <= Z <= 20. The GRASP
(general-purpose relativistic atomic structure package) is adopted for
calculating energy levels and radiative rates, while for determining the
collision strengths and subsequently the excitation rates, the Dirac atomic
R-matrix code DARC is used. Oscillator strengths, radiative rates, and line
strengths are reported for all E1, E2, M1, and M2 transitions among the lowest
24 levels of the Li-like ions considered. Collision strengths have been
averaged over a Maxwellian velocity distribution, and the effective collision
strengths obtained are reported over a wide temperature range up to 10$^{7.4}$
K. Additionally, lifetimes are also listed for all calculated levels of the
above ions. Finally, extensive comparisons are made with available results in
the literature, as well as with our parallel calculations for all parameters
with the Flexible Atomic Code FAC in order to assess the accuracy of the
reported results.
