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1	Tidsberoende kvantkemiska beräkningar av optisk absorption hos polymerer och molekyler med litet bandgap / Calculations of optical absorption in low-bandgap polymers and molecules using time-dependent quantum chemical methods Södergren, Helena January 2004 (has links) <p>The vertical electronic excitation energies for the narrow-bandgap polymers LBPF, EP37 and EP62 have been calculated using Density Functional Theory (DFT). Also the vertical excitation energies for the acceptor unit of LBPF have been calculated using the Hartree-Fock (HF), DFT and Coupled Cluster (CC) methods. The calculations cover the visible and infrared wave length region and two strong transitions are obtained, one corresponding to the pi to pi* transition and one corresponding to the pi to Acceptor transition. The excitation energies obtained from DFT are below the corresponding experimental results and attempts have therefore been made to perform bench-marking calculations using a hierarchy of CC methods.</p> Physics Plastic solar cells low bandgap polymers absorption spectra Hartree-fock method Density functional theory Coupled cluster methods Fysik Physics Fysik
2	Theoretical studies of optical absorption in low-bandgap polymers / Teoretiska studier av optisk absorption i polymerer med låga bandgap Karlsson, Daniel January 2005 (has links) <p>The absorption spectra of a recently designed low-bandgap conjugated polymer has been studied using the semi-empirical method ZINDO and TDDFT/B3LYP/6-31G. The vertical excitation energies have been calculated for monomer up to hexamer. Two main absorption peaks can be seen, the one largest in wavelength corresponding to a HOMO to LUMO transition, and one involving higher order excitations. TDDFT results are red-shifted compared to the ZINDO results. Comparison with experiment yields that short conjugation lengths are dominating. This is possibly due to steric interactions between polymer chains, breaking the conjugation length. Such effects are also studied.</p> ZINDO Density functional theory Hartree Fock method Low bandgap polymers Absorption spectra Semi empirical methods Plastic solar cells Computational physics Beräkningsfysik
3	Tidsberoende kvantkemiska beräkningar av optisk absorption hos polymerer och molekyler med litet bandgap / Calculations of optical absorption in low-bandgap polymers and molecules using time-dependent quantum chemical methods Södergren, Helena January 2004 (has links) The vertical electronic excitation energies for the narrow-bandgap polymers LBPF, EP37 and EP62 have been calculated using Density Functional Theory (DFT). Also the vertical excitation energies for the acceptor unit of LBPF have been calculated using the Hartree-Fock (HF), DFT and Coupled Cluster (CC) methods. The calculations cover the visible and infrared wave length region and two strong transitions are obtained, one corresponding to the pi to pi* transition and one corresponding to the pi to Acceptor transition. The excitation energies obtained from DFT are below the corresponding experimental results and attempts have therefore been made to perform bench-marking calculations using a hierarchy of CC methods. Physics Plastic solar cells low bandgap polymers absorption spectra Hartree-fock method Density functional theory Coupled cluster methods Fysik Physics Fysik
4	Theoretical studies of optical absorption in low-bandgap polymers / Teoretiska studier av optisk absorption i polymerer med låga bandgap Karlsson, Daniel January 2005 (has links) The absorption spectra of a recently designed low-bandgap conjugated polymer has been studied using the semi-empirical method ZINDO and TDDFT/B3LYP/6-31G. The vertical excitation energies have been calculated for monomer up to hexamer. Two main absorption peaks can be seen, the one largest in wavelength corresponding to a HOMO to LUMO transition, and one involving higher order excitations. TDDFT results are red-shifted compared to the ZINDO results. Comparison with experiment yields that short conjugation lengths are dominating. This is possibly due to steric interactions between polymer chains, breaking the conjugation length. Such effects are also studied. ZINDO Density functional theory Hartree Fock method Low bandgap polymers Absorption spectra Semi empirical methods Plastic solar cells Computational physics Beräkningsfysik

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