Theoretical Calculations of Second and Third-Order Nonlinear Susceptibilities and Their Corresponding Hyperpolarizabilities of a Styrylquinolinium Dye

The second (chi((2))(exp)) and third-order (chi((3))(exp)) susceptibilities of a styrylquinolinium dye (1) have been determined utilizing second-harmonic generation (SHG) and third-harmonic generation (THG) techniques, respectively. The reported measurement findings on chi((2))(exp) and chi((3))(exp) have been compared with the theoretical data evaluated here by means of ab-initio quantum mechanical calculations. The electric dipole moments (mu), static dipole polarizabilities (alpha) and first hyperpolarizabilities (beta) have been computed by density functional theory (DFT) at B3LYP/6-311+G(d, p) level. To reveal the frequency-dependent second and third-order microscopic nonlinear optical (NLO) behavior of the title compound, the dynamic dipole polarizabilities, first and second (gamma) hyperpolarizabilities have been theoretically investigated using time-dependent Hartree-Fock (TDHF) method. According to the experimental and theoretical results, the values of susceptibilities and the corresponding microscopic coefficients with large non-zero responses make the examined dye promising candidate for NLO applications.