Consistent scheme for computing standard hydrogen electrode and redox potentials.

The standard hydrogen electrode (SHE) potential in aqueous solution was evaluated with new computational procedure that provides the Gibbs energy of a proton in aqueous solution from the experimental pK(a) value and the Gibbs energy change by deprotonation reactions of several neutral alcohol molecules. With our computational scheme, the CCSD(T)/aug-cc-pVDZ method provides the SHE potential of 4.52 V, which is almost the same as the experimental SHE potential. This scheme also reproduces well the redox potentials of several typical reactions within almost 0.1 V. B3LYP also gives excellent redox potentials of the same reactions with almost the same accuracy with our new computational scheme.