Determination of dipole polarizabilities and second hyperpolarizabilities in alkynyl-ruthenium complexes using quantum-chemical calculations

To investigate dispersion-free third-order nonlinear optical (NLO) behaviour of a series of ruthenium complexes, static dipole polarizabilities (α) and second hyperpolarizabilities (γ) have been determined by time-dependent Hartree-Fock (TDHF) method. To provide an insight into the frequency-dependent third-order NLO phenomena of the title compounds, the dynamic dipole polarizabilities and second hyperpolarizabilities using TDHF procedure have been also computed at the wavelengths used in third-harmonic generation (THG) measurements. According to the computation results, the examined molecules exhibit second hyperpolarizabilities with non-zero values, implying microscopic third-order NLO behaviour. To compare our theoretical results on third-order NLO manner with corresponding experimental data, we also give the calculation results of the dynamic third-order susceptibilities (χ⁽³⁾) for the studied complexes.