where formula_6 represents the position-dependent dielectric, formula_7 represents the electrostatic potential, formula_8 represents the charge density of the solute, formula_9 represents the concentration of the ion "i" at a distance of infinity from the solute, formula_10 is the valence of the ion, "q" is the charge of a proton, "k" is the Boltzmann constant, "T" is the temperature, and formula_11 is a factor for the position-dependent accessibility of position "r" to the ions in solution (often set to uniformly 1). If the potential is not large, the equation can be linearized to be solved more efficiently.