Absorption profiles in Hα line at mid-transit in units of Doppler velocity obtained in test simulations: when the stellar flux in VUV range is put to zero (red); when the residual energy of newly created electrons is put to zero (instead of 1.5kT_e, green); when the recombination heating is put to zero (blue). For comparison, the black line shows the Hα absorption profile calculated with the fiducial set of the model parameters N5.