Effects of the radiation field intensity. Physical properties as a function of A_V for models in thermal equilibrium and constant pressure fixed at 10^6.5 K cm⁻³, with solar metallicity, turbulent velocity 10 km s⁻¹, and different values of X-ray radiation field intensity: G_X = 10⁻¹ (left column), G_X = 10¹ (central column) and G_X = 10² (right column). Top row: gas temperatures. Second row: total hydrogen density in black and ionization fraction (n_e/n_H) in blue. Third row: relative abundances of hydrogen. Bottom row: relative abundances of carbon (yellow), oxygen (blue), sulfur (green), and CO (black). The white background indicates the ionized phase, the gray background the atomic phase, and the dark gray the molecular phase. The transition from ionized to atomic phases and that from atomic to molecular correspond to density ratios of e⁻/H⁰ = 1 and H⁰/H₂ = 1, respectively.