The theoretical analyses of the ratio of the deuterium to hydrogen termination on the Si(111) surface for the passivation both in the gas of D₂ or H₂ molecules and in the deuterated or hydrogenated electrolyte, has been carried out. For the gas phase passivation, the equilibrium concentrations of D(H) adatoms are found from the equality of the chemical potential of D(H) on the Si surface to that in the D₂ (H₂) gas. For wet passivation, the concentrations of adatoms are calculated from the condition of the equilibrium for the electrochemical reaction of the D⁺ (H⁺) ion adsorption from the electrolyte (discharge reaction) in the case of thermodynamic equilibrium in the electrolytic system, and from the equality of the discharge reaction rate to the rate of the electrochemical desorption reaction in the case of the steady-state conditions at the cathodic overpotential. The reaction rates are considered with using of the quantum mechanical theory of the elementary act of proton transfer reactions [1]. Both for gas passivation and for wet passivation, it is shown that the ratio of D- to H-adatom concentrations depends on the differences of the configuration chemical potentials of the relevant isotope components. The vibrational contributions to the adatom chemical potentials are calculated more exactly than it was done before in [2]. That results in the significant reduction of the calculated termination ratio for the gas passivation compared to the results of [2]. For all the considered passivation techniques, the ratio of D- to H-adatom concentrations is about 1 if the deuterium passivation and the hydrogen passivation are performed at the same conditions (the same thermodynamic parameters, the same overpotentials).