The consistency analysis of different semiempirical calculations on second- and third-order nonlinear optical properties of donor–acceptor chromophores containing α-cyan

Abstract

The static and frequency dependent average polarizability (< α>), first- and second-hyperpolarizabilities (< β> and < γ>) and HOMO and LUMO energies of donor–acceptor chromophores containing α-cyan ( 1a– c) have been investigated by using the AM1, MNDO, MNDO-d, PM3, RM1 and PM6 methods within a time-dependent Hartree–Fock (TDHF) approaches. The electronic properties of 1a– c have been reported by employing two-state model calculated at ZINDO/S-SCI, PM3-SCI and RM1-SCI methods. Also, the molecular hardness ( η) and electronegativity ( χ) parameters have been obtained by using molecular frontier orbital energies. The < α>, < β>, < γ> HOMO, LUMO energies, η and χ parameters have been investigated with respect to the choice of different semiempirical methods. The variation graphics of β, β 0, η and χ parameters according to the different semiempirical methods are presented. Furthermore, the variation graphics of β 0 with regard to the μ eg , Δ μ and λ eg are displayed. The frontier molecular orbital and electrostatic potential pictures of 1a– c using ZINDO/S-SCI level have been examined. The results of 1a– c display significant second- and third-order molecular nonlinearity.