Solvent Effects on the First Hyperpolarizabilities of Some Organic Chromophores: An Ab Initio Study with Self-Consistent Reaction Field (SCRF) Method

• Main Authors: Yi-Han Yang, 楊逸涵
• Other Authors: Shyi-Long Lee
• Format: Others
• Language: en_US
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/64051948061738683357

碩士 === 國立中正大學 === 化學研究所 === 88 === The molecular hyperpolarizabilities of pi-conjugated, donor-acceptor chromophores are calculated using self-consistent reaction field (SCRF) method with 6-31G, 6-31G* and 6-31+G* basis sets. Considering the solvent environment, the energy terms of the perturbation theory are corrected for solvent effects by means of two continuum cavity models, the Onsager model and the PCM model, in the SCRF theory. In this thesis, we use five compounds: para-nitroaniline (p-NA, 1), 1-(N,N-dimethylamino)-4-nitrobenzene (2), 1-(N,N-dimethylamino)-4-[2-(4-nitrophenyl)ethenyl]benzene (3), {[4-(N,N-dimethylamino)phenyl]methylidene}propanedinitrile (4) and 2-[(4-nitrophenyl)methylidene]-1,3-dithiole (5) It is observed that after optimization under solvated environment with different dielectric constants, no significant changes in the geometries are visualized. Moreover, with the increase in the dielectric constant, the hyperpolarizability and dipole moment of the chromophores increase while the HOMO-LUMO gap decreases. Further, a saturation limit can be noticed with higher dielectric constants. It would be carried out about the dependence of the HOMO-LUMO gap upon the first hyperpolarizabilities with solvent effects involved.