Calculation of the first hyperpolarizabilities of the neutral and the cationic form of a donor–acceptor molecule containing octamethylferrocene

Abstract

The first hyperpolarizabilities β of a redox pair of molecules, containing an octamethylferrocene donor linked by an ethenyl chain to a nitrothiophene acceptor, calculated at the SCF level, predict a much larger β value for the cation than for the reduced form, which is in contradiction to previous experimental findings. It is shown that the ground state of the oxidised form cannot be described by a single reference configuration. A multi-configurational description of the cation leads to a much smaller value for the dominant component of β, bringing the relative computed values in qualitative agreement with experiment.