Photospheric (at the Rosseland mean optical depth, τ_R = 2/3) abundance of species in the atmosphere of hydrogen white dwarf of log g = 8 as a function of the effective temperature. Different colors and lines represent different species as indicated in the legend insert. The panels show results with (left) and without (middle) H⁺₃ species considered. The right panel shows the result obtained by assuming formation of a hypothetical anionic species (represented by H⁺₂ with the decreased formation energy).