Electronic Excited States of Tetracyanonickelate(II)

We revisit the assignment of the absorption spectrum of tetracyanonickelate(II) by calculating energies of excitations with time-dependent density functional theory. Our results give strong evidence that the original assignment of the spectrum is only partially correct. We thus propose an alternative assignment consistent with our theoretical calculations and all available experimental evidence. In particular, we reassign the bands at 22 400 and 32 300 cm-1 to the ^1A_(1g) → ^3A_(2g) (b_(2g) → b_(1g)) and ^1A_(1g) → ^1A_(2g) (b_(2g) → b_(1g)) excitations.