Synthetic Si iii line profiles computed for Spica with the TLUSTY stellar atmosphere models for T_eff and log g appropriate to each surface element and Doppler-shifted using the surface velocity field computed with TIDES. The three spectra correspond to microturbulent velocities v_turb = 2 (dots), 10 (dashes) and 15 (continuous) km s^-1 and illustrate how the larger values of this parameter produce greater line-strength in the Si iii λ 4552 line. The lines originating in the primary and secondary are indicated with m₁, and m₂ respectively. The depicted profiles correspond to orbital phase φ = 0.75.