Performances of recently-proposed functionals for describing disulfide radical anions and similar systems (original) (raw)

Two-center three-electron anions have been reported as a pitfall case for density functional theory, owing to their important dynamical correlation and the inherent difficulty of a balanced description of odd-vs. even-number electron bonds. The critical roles of the correlation functional, and of the amount of exact Hartree-Fock exchange included are investigated in order to pinpoint the most efficient approach for simulating disulfide radical anions (ease of formation and inter-sulfur distances). Several recently-developed functionals, such as B1B95, BMK, B2PLYP(D) and numerous range-separated hybrid yield a quantitatively correct description, and offer a pragmatic and superior solution to the Becke's half-and-half usually recommended for this delicate situation.