Benchmark study of the performance of density functional theory for reduction potentials of vanadium compounds

A systematic benchmark study was performed for the first time to investigate the performance of density functional theory for calculation of reduction potentials of vanadium compounds. Six density functionals of different types were selected for testing: local OLYP and M06L, global hybrid O3LYP and B3LYP, as well as, meta-hybrid functionals TPSSh and M06. Local and hybrid functionals with a relatively high contribution of Hartree-Fock exchange showed unsatisfactory results. In particular, the widely used hybrid functional B3LYP for the transformation VIII→VII occurring in the vanadium redox flow battery yields a negative value of the standard potential instead of a positive one. Among the tested functionals the smallest deviation from the experimental data provides the meta-hybrid functional TPSSh with a 10% contribution of the Hartree-Fock exchange. The computational protocol to calculate redox potentials of vanadium compounds is suggested.