Radial profiles of gaseous fractional abundances of H₂O, O₂, and OH, andicy fractional abundances of H₂O in the NGC 1333-IRAS 4A envelope models. The light green solid lines, the cyan double-dashed dotted lines, and the blue dotted lines show the radial profiles of our standard model calculations, for values of central star X-ray luminosities L_X =10²⁸, 10³⁰, and 10³² erg s⁻¹, respectively (see also Figs. 3, 4, 5, 6). The yellow dashed double-dotted lines, the scarlet dashed dotted lines, and the brown dashed lines show the radial profiles of our additional model calculations for L_X = 10²⁸, 10³⁰, and 10³² erg s⁻¹, respectively. In the additional model calculations, we include the photodesorption by UV photons generated internally via the interaction of secondary electrons produced by X-rays with H₂ molecules (the secondary (indirect) X-ray-induced photodesorption, see Figs. G.1and G.2), and we also switch off the direct X-ray-induced photodesorption (see also Fig. G.3). In the top left panel, the observational best-fit H₂O gas abundance profile obtained in van Dishoeck et al. (2021) is overplotted with the black solid line (see also Fig. 10). In the bottom left panel, the three model O₂ gas abundance profiles obtained in Yıldız et al. (2013) are overplotted (see also Fig. 10).