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Stuttgart, Germany

Klamt A.,COSMOlogic GmbH | Klamt A.,University of Regensburg
Wiley Interdisciplinary Reviews: Computational Molecular Science | Year: 2011

The conductor-like screening model COSMO, a variant of the dielectric continuum solvation models, has become very popular due to its algorithmic simplicity, numerical stability, and its great insensitivity with respect to outlying charge errors. The advanced model COSMO-RS, i.e., COSMO for realistic solvation, is a statistical thermodynamics theory based on COSMO polarization charge densities, which overcomes many of the limitations and theoretical shortcomings of dielectric continuum models. Due to its ability to treat mixtures at variable temperatures, it has become very popular in chemical engineering and in wide areas of physical and medicinal chemistry. COSMO-RS currently may be considered as the most accurate model for the prediction of solvation energies. This article provides a short description of the basic concepts of both the models, of the differences with other solvation models and of their application areas. Finally, direct COSMO-RS, a recent direct integration of the COSMO-RS concept into quantum chemical calculations, is briefly described. © 2011 John Wiley & Sons, Ltd. Source


Hellweg A.,COSMOlogic GmbH
Journal of Computational Chemistry | Year: 2013

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 operational modes are possible thereby: intrinsic (IRC) and dynamic reaction coordinate calculations (DRC). The technical difference between these modes is that in an IRC calculation the kinetic energy of the nuclei is quenched while the total energy is conserved in DRC calculations. In this work, a heuristic control methodology of atomic kinetic energies in DRC calculations using fuzzy logic is proposed. A diversified test set of 10 reactions has been collected to examine the performance of this approach. Fuzzy rule-based models are found to be a convenient way to make the determination of accessible paths of chemical reactions computationally efficient. © 2013 Wiley Periodicals, Inc. Source


Hellweg A.,COSMOlogic GmbH
Journal of Chemical Physics | Year: 2011

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, Mller-Plesset perturbation theory, MP2, and the algebraic diagrammatic construction through second-order, ADC(2), are discussed together with the spin-component scaled and the scaled opposite-spin variants of these methods. The computed dipole moments show a very good correlation with data from high-resolution spectroscopy. Compared to the unscaled methods, the spin-component scaling increases the accuracy of the results and improves the robustness of the calculations. An accuracy about 0.2 to 0.1 D in the ground state and about 0.3 to 0.2 D in the electronically excited states can be achieved with these approaches. © 2011 American Institute of Physics. Source


Grant
Agency: Cordis | Branch: H2020 | Program: RIA | Phase: NMP-20-2014 | Award Amount: 3.67M | Year: 2015

The lifetime, reliability, and efficiency of organic light emitting diodes (OLED) are critical factors precluding a number of novel devices from entering the market. Yet, these stability issues of OLEDs are poorly understood due to their notorious complexity, since multiple degradation and failure channels are possible at different length- and timescales. Current experimental and theoretical models of OLED stability are, to a large extent, empirical. They do not include information about the molecular and meso-scales, which prevents their integration into the workflow of the industrial R&D compound design. It is the idea of this project to integrate various levels of theoretical materials characterization into a single software package, to streamline the research workflows in order for the calculations to be truly usable by materials engineers, complementary to experimental measurements. Towards this goal, this project brings together the academic and industrial expertise of the leading experimental and theoretical groups in the field of organic semiconductors.


Klamt A.,COSMOlogic GmbH | Klamt A.,University of Regensburg | Eckert F.,COSMOlogic GmbH | Arlt W.,Sudan University of Science and Technology
Annual Review of Chemical and Biomolecular Engineering | Year: 2010

The conductor-like screening model for realistic solvation (COSMO-RS) method has been established as a novel way to predict thermophysical data for liquid systems and has become a frequently used alternative to force field - based molecular simulation methods on one side and group contribution methods on the other. Through its unique combination of a quantum chemical treatment of solutes and solvents with an efficient statistical thermodynamics procedure for the molecular surface interactions, it enables the efficient calculation of many properties that other methods can barely predict. This review presents a short delineation of the theory, the application potential and limitations of COSMO-RS, and its most important application areas. Copyright © 2010 by Annual Reviews. All rights reserved. Source

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