title: Accurate calculated optical properties of substituted quaterphenylene nanofibers.
abstract: The accurate prediction of both excitation and emission energies of substituted p-quaterphenylenes using a variety of established and newly developed density functional methods is evaluated and compared against experimental data, both from single molecules and from nanofibers. For calculation of the UV-vis excitation the MPW1K functional is the best performing method (with the employed TZVP basis set). After a linear scaling factor is applied, mPW2-PLYP, CIS and the very fast INDO/S also reproduce the experimental data correctly. For the fluorescence relaxation energies MPW1K, mPW2-PLYP, and INDO/S give good results, even without scaling. However, mPW2-PLYP involves second-order perturbation to introduce nonlocal electron correlation and therefore requires significantly more resources, so the recommended level of theory for a single methodology to investigate the optical properties of substituted phenylenes and related systems is MPW1K/6-311+G(2d,p), followed by INDO/S as a low-cost alternative. As an extension of a previous work on predicting first hyperpolarisabilities, we can now demonstrate that the chosen approach (HF/6-31G(d)//B3LYP/6-31G(d)) produces data that correlate well with the susceptibilities derived from measurements on nanofibers.
authors.affiliation: Institut fur Reine und Angewandte Chemie und Center of Interface Science, Carl von Ossietzky Universitat Oldenburg, PO Box 2503, 26111 Oldenburg, Germany.
authors.forename: Justin J
authors.initials: JJ
authors.lastname: Finnerty
authors.forename: Rainer
authors.initials: R
authors.lastname: Koch
mesh_terms: D003198:Computer Simulation; D008956:Models, Chemical; D057139:Nanofibers / Q000737:chemistry*; D055095:Optics and Photonics; D011108:Polymers / Q000737:chemistry*
chemical_list: D011108:Polymers; C041325:polyphenylene sulfide