Penile retroversion and partial phallectomy performed in a standing horse.
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M Hanrath
Publications and source records attributed to M Hanrath.
Individually selecting multi-reference CI and its application to biradicalic cyclizations.
In the present review a new algorithm to perform individually selecting MR-CI calculations is discussed. The new algorithm exploits the advantages arising from the subdivision of the molecular orbitals (MOs) into an internal and an external part and avoids the recalculation of representation matrices by the use of a specially designed cache. With the new algorithms we are able to perform calculations including more than 10 million selected configurations state functions (CSFs) as a matter of routine. As an example for the possibilities of the new approach the regioselectivity of thermal biradical cyclizations (C2-C7 vs. C2-C6 cyclization) is investigated in the second part of the present work. After studying the accuracy of various quantum chemical methods (MR-CI, density functional theory, and coupled cluster approaches) using (Z)-1,2,4 Heptatriene-6-yne as a model system the influence of substituents (R = H, Ph, t-Bu, NH2) on the regioselectivity is investigated. Our results rationalize the switch between the two biradical cyclizations on the basis of mainly steric (t-Bu) or electronic (Ph) substituent effects. Moreover, the results for R = NH2 predict that the activation energy of the C2-C6 cyclization can be lowered even more. However, a change in the reaction mechanism is found.
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Ab Initio Investigation of the ellipsis pi(2)(g) (X(3)Sigma(-)(g), 1(1)Delta(g), 1(1)Sigma(+)(g)) Electronic States of NCN. Study of the Renner-Teller Effect in the 1(1)Delta(g) State.
Large-scale CI calculations are carried out to obtain accurate potential energy surfaces for the ellipsis pi(2)(g) manifold (X(3)Sigma(-)(g), 1(1)Delta(g), 1(1)Sigma(+)(g)) of electronic states of NCN. Separation of the low-lying singlet states from the triplet ground state is computed in close agreement with the results of a recent photoelectron study by T. R. Taylor, R. T. Bise, K. R. Asmis, and D. M. Neumark [Chem. Phys. Lett. 301, 413-416 (1999)]. Vibronic coupling (Renner-Teller effect) in the 1(1)Delta(g) state is studied by means of a perturbative and a variational approach. Results of the present ab initio study confirm explicitly the rho(4) dependence postulated for the splitting of bending potential curves in Delta electronic states at small deviations from linearity. Copyright 2000 Academic Press.
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