This work reports on radiative transition rates and electron impact excitation collision strengths for levels of the 3s^2^3p, 3s3p^2^, 3s^2^4s, and 3s^2^3d configurations of Si II. The radiative data were computed using the Thomas-Fermi-Dirac-Amaldi central potential, but with the modifications introduced by Bautista (2008, J. Phys. B: Atom. Mol. Opt. Phys., 41, 065701) that account for the effects of electron-electron interactions. We also introduce new schemes for the optimization of the variational parameters of the potential. Additional calculations were carried out with the Relativistic Hartree-Fock and the multiconfiguration Dirac-Fock methods. Collision strengths in LS-coupling were calculated in the close coupling approximation with the R-matrix method. Then, fine structure collision strengths were obtained by means of the intermediate-coupling frame transformation (ICFT) method which accounts for spin-orbit coupling effects.