@article{WortmannSalehEngelsPeyerimhoff1994, author = {Wortmann-Saleh, D. and Engels, Bernd and Peyerimhoff, S. D.}, title = {Theoretical Study of the Reaction O(\(^3\)P) + C\(_2\)H\(_4\) and comparison with the \(^3\)CH\(_3\) + C\(_2\)H\(_4\) Reaction}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59076}, year = {1994}, abstract = {The minimum energy path for the reaction O(\(^3\)P\(_g\)) + C\(_2\)H\(_4\)(\(^1\)A\(_g\)) has been calculated by optimizing all relevant geometrical parameters along the approach of oxygen to ethene. A barrier of 4.7 kcal/mol in the \(^3\)A"( ... 9a'\(^2\)- 10a'3a") potential energy surface and an energy difference of 14.4 kcal/mol between the product and the fragments is found at the multireference-configuration interaction level. The corresponding values at the lower-level treatment CASSCF are 9 kcal/mol for the barrier and 9 kcal/mol for the depth of the potential; this shows the importance of inclusion of electron correlation. The barrier for CH\(_2\) rotation for the lowestenergy structure (asymmetric OC\(_2\)H\(_4\)) is around 5 kcal/mol. The energy gap to the first excited state \(^3\)A'( ... 9a'l0a'3a'12) is found tobe 3.6 kcal/mol in MRD-CI calculations at the ground-state minimum. Comparison with \(^3\)CH\(_2\) + C\(_2\)H\(_4\) shows that in this system the lowest-energy surface is \(^3\)A', i.e., the state which is the excited state in 0 + C\(_2\)H\(_4\). This difference in energy ordering of \(^3\)A' and \(^3\)A" states results from the fact that the p\(_x\), p\(_y\), p\(_z\) degeneracy of oxygen orbitals is lifted in \(^3\)CH\(_2\)leading to b\(_1\), b\(_2\). and a\(_1\) MOs whereby the lowest b\(_2\) (a") remains doubly occupied; as a consequence, the reaction pattem between the oxygen and \(^3\)CH\(_2\) approach is different, which is also quite apparent in the calculated charge transfer.}, subject = {Organische Chemie}, language = {en} } @article{VolzShinPrinzbachetal.1978, author = {Volz, H. and Shin, J.-H. and Prinzbach, H. and Babsch, H. and Christl, Manfred}, title = {Stability of Tricyclo[4.1.0.0\(^{2,7}\)]heptenyl-Cations}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58001}, year = {1978}, abstract = {No abstract available}, subject = {Organische Chemie}, language = {en} } @article{SuterPlessErnzerhofetal.1994, author = {Suter, H. U. and Pleß, V. and Ernzerhof, M. and Engels, Bernd}, title = {Difficulties in the Calculation of Electron Spin Resonance Parameters using Density Functional Methods}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59113}, year = {1994}, abstract = {Density functional theory is applied to the calculation ofthe isotropic byperfine coupJing constants in some small molecules. Various functionals are tested. The agreement of the calculated values to experimental data and values obtained from sophisticated ab initio methods depends on the functionals used and the system under consideration. With respect to spin density calculations the functional of Lee, Yang and Parr with Becke's excbange functional (BLYP) is found to give good results for tbe heavier center of the CH and the NH molecule, while the spin densities of other molecules such as OH, H\(_2\)CN, H\(_2\)CO\(^+\), NO and O\(_2\) deviate considerably from experimental and/or other theoretical results (30\%-60\%). In cases where the singly occupied orbital can contribute to the isotropic hyperfine coupling constants, accurate results are obtained. The reason fortbis is analyzed.}, subject = {Organische Chemie}, language = {en} } @article{SuterHuangEngels1994, author = {Suter, H. U. and Huang, M.-B. and Engels, Bernd}, title = {A Multireference Configuration Interaction Study of the Hyperfine Structure of the Molecules CCO, CNN and NCN in their triplet ground states}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59108}, year = {1994}, abstract = {The hyperfine structures of the isoelectronic molecules CCO. CNN, and NCN in their triplet ground states (X\(^3 \sum ^-\)) are investigated by means of ab initio methods. The infrared frequencies and geometries are detennined and compared with experiment. Configuration selected multireference configuration interaction calculations in combination with perturbation theory to correct the wave function (MRD-CI/B\(_K\)) employing extended atomic orbital (AO) basis sets yielded very accurate hyperfine properties. The theoretical values for CCO are in excellent agreement with the experimental values determined by Smith and Weltner [J. Chem. Phys. 62,4592 (1975)]. For CNN, the first assignment of Smith and Weltner for the two nitrogen atoms has to be changed. A qualitative discussion of the electronic structure discloses no simple relation between the structure of the singly occupied orbitals and the measured hyperfine coupling constants. Vibrational effects were found to be of little importance.}, subject = {Organische Chemie}, language = {en} } @article{SuterEngels1994, author = {Suter, H. U. and Engels, Bernd}, title = {Theoretical investigation of ESR parameters: H\(_2\)CN and H\(_2\)CO\(^+\)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59029}, year = {1994}, abstract = {The hyperfine structure of the two isoelectronic molecules H\(_2\)CN and H\(_2\)CO\(^+\) in their electronic ground state (X\(^2\)B\(_2\)) is studied. The influence of the atomic orbital (AO), basis sets, of the correlation treatment, and of the. equilibrium geometry on the obtained hyperfine propertles 1s - investigated. It is found that the multireference double excitation-configuration interaction (MRD-CI)/ BK treatment in which an MRD-CI wave function is corrected by a modified B\(_K\) method yields equivalent results to quadratic CI [QCISD(T)], coupled cluster single doubles [CCSD(T)), or Brueckner doubled [BD(T)]. Uncertainties in the equilibrium geometries are found to be the major source for discrepancies between theoretically and experimentally determined isotropic hyperfine coupling constants (hfccs). For the heavier centers, the calculated values of the isotropic hfccs agrees nearly perfectly with experimental values (\(\approx\) 1\%-2\%). The calculated values for the hydrogens are too low, but using the equilibrium structure suggested by Yamamoto and Sato [J. Chem. Phys. 96, 4157 ( 1992)], the best estimate deviates by less than 3\%.}, subject = {Organische Chemie}, language = {en} } @article{StanglJelinekFinkChristl1992, author = {Stangl, R. and Jelinek-Fink, H. and Christl, Manfred}, title = {Darstellung phenylsubstituierter Derivate des Tricyclo[4.1.0.0\(^{2,7}\)]heptans und des 1,2,3,4-Tetrahydro-1,2,3-methenonaphthalins}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58610}, year = {1992}, abstract = {No abstract available}, subject = {Organische Chemie}, language = {de} } @article{StaikovaPericEngelsetal.1994, author = {Staikova, M. and Peric, M. and Engels, Bernd and Peyerimhoff, S. D.}, title = {Ab initio Investigation of the Structure of the X\(^2\)A', A\(^2\)A'' (1\(^2\)Π) Spectral System of HCO: Investigation of the Magnetic Hyperfine Effects}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59089}, year = {1994}, abstract = {Results ofan ab initio study ofthe hyperfine structure of the X\(^2\)A', A\(^2\) A" ( 1\(^2 \Pi\)) system ofthe formyl radical are presented. Special attention is paid to the analysis of the interplay between the vibronic and magnetic hyperfine etfects. The results of computations are in very good agreement with the available experimental findings. The values for the hyperfine coupling constants in lower bending Ievels of both electronic species are predicted.}, subject = {Organische Chemie}, language = {en} } @article{StaikovaEngelsPericetal.1993, author = {Staikova, M. and Engels, Bernd and Peric, M. and Peyerimhoff, S. D.}, title = {Ab initio calculation of the vibronically averaged hyperfine coupling constants in the two lowest electronic states of H\(_2\)O\(^+\)}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-58998}, year = {1993}, abstract = {No abstract available}, subject = {Organische Chemie}, language = {en} } @article{StaikovaEngelsPeric1994, author = {Staikova, M. and Engels, Bernd and Peric, M.}, title = {Ab initio investigation of the hyperfine structure in the 1\(^2\)Π\(_u\)(X\(^2\)A\(_1\), A\(^2\)B\(_1\) system of BH\(_2\))}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-59000}, year = {1994}, abstract = {No abstract available}, subject = {Organische Chemie}, language = {en} } @phdthesis{Schmidt2011, author = {Schmidt, Ralf}, title = {Hamilton-Receptor-Mediated Self-Assembly of Merocyanine Dyes into Supramolecular Polymers}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-56265}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2011}, abstract = {Die Selbstorganisation von Merocyaninfarbstoffen zu supramolekularen Polymeren wurde untersucht. Dabei konnte die Anordnung der hoch dipolaren Farbstoffe durch die Verwendung von verschiedenen Kombinationen von Wasserstoffbr{\"u}ckenbindungsmotiven und dipolarer Aggregation der Chromophore gesteuert.}, subject = {Selbstorganisation}, language = {en} }