Arnim Hellweg

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The removal of implant coatings may be necessary if rough implant surfaces are exposed subgingivally due to progressive peri-implant bone loss or if they are also supragingivally exposed because of progressive gingival recession, thus facilitating plaque formation and impairing tooth cleaning done at home. The aim of this experimental study was to develop(More)
We herein present the graphical user interface (GUI) TmoleX for the quantum chemical program package TURBOMOLE. TmoleX allows users to execute the complete workflow of a quantum chemical investigation from the initial building of a structure to the visualization of the results in a user friendly graphical front end. The purpose of TmoleX is to make(More)
The magnesium atom of chlorophylls (Chls) is always five- or six-coordinated within chlorophyll-protein complexes which are the main light-harvesting systems of plants, algae and most photosynthetic bacteria. Due to the presence of stereocenters and the axial ligation of magnesium the two faces of Chls are diastereotopic. It has been previously recognized(More)
We present a parallel implementation of second-order Møller-Plesset perturbation theory with the resolution-of-the-identity approximation (RI-MP2). The implementation is based on a recent improved sequential implementation of RI-MP2 within the Turbomole program package and employs the message passing interface (MPI) standard for communication between(More)
Quantum-chemical calculations with the approximate coupled-cluster singles-and-doubles model CC2 have been carried out for 1-tert-butyl-6-cyano-1,2,3,4-tetrahydroquinoline (NTC6). For this molecule dual fluorescence was experimentally observed, raising the discussion about the importance of the amino twist angle for this process. The calculations suggest(More)
The microwave spectrum of m-cresol (3-methylphenol) has been investigated using a molecular beam Fourier transform microwave spectrometer in the frequency range from 3 to 26.5 GHz. The rotation of the hydroxy group into two different unequal energetic minima leads to different spectra for the syn- and anticonformers. Because of a high potential barrier both(More)
The overall rotation and internal rotation of p-cresol (4-methyl-phenol) has been studied by comparison of the microwave spectrum with accurate ab initio calculations using the principal axis method in the electronic ground state. Both internal rotations, the torsions of the methyl and the hydroxyl groups relative to the aromatic ring, have been(More)
For the understanding and prediction of chemical reactions, detailed knowledge of the minimum energy path between reactants and transition state is of utmost importance. Stewart et al. (J. Comput. Chem. 1987, 8, 1117) proposed the usage of molecular trajectories calculated from Newton's equations of motion for an efficient reaction path following. Two(More)
We report optimized auxiliary basis sets for use with the Karlsruhe segmented contracted basis sets including moderately diffuse basis functions (Rappoport and Furche, J. Chem. Phys., 2010, 133, 134105) in resolution-of-the-identity (RI) post-self-consistent field (post-SCF) computations for the elements H-Rn (except lanthanides). The errors of the RI(More)
The accuracy of dipole moments calculated from wave function methods based on second-order perturbation theory is investigated in the ground and electronically excited states. Results from the approximate coupled-cluster singles-and-doubles model, CC2, Møller-Plesset perturbation theory, MP2, and the algebraic diagrammatic construction through second-order,(More)