Breit-Pauli transition probabilities for SII

The collision strengths have been calculated in the close-coupling approximation using the B-spline Breit-Pauli R-matrix method. The multiconfiguration Hartree-Fock method with term-dependent non-orthogonal orbitals is employed for an accurate representation of the target wave functions.

The close-coupling expansion includes 70 bound levels of SII covering all possible terms of the ground 3s^2^3p^3^ and singly excited 3s3p^4^, 3s^2^3p^2^3d, 3s^2^3p^2^4s, and 3s^2^3p^2^4p configurations. The present calculations are more extensive than previous ones, leading to a total 2415 transitions between fine-structure levels. The effective collision strengths are obtained by averaging the electron collision strengths over a Maxwellian distribution of velocities and these are tabulated for all fine-structure transitions at electron temperatures in the range from 5000 to 100000K.