Thorsten Koeddermann

Thorsten Koeddermann
Hochschule Bonn-Rhein-Sieg · Department of Electrical Engineering, Mechanical Engineering, and Technical Journalism (EMT)

PhD, Physical Chemistry

About

37
Publications
5,599
Reads
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1,616
Citations
Citations since 2016
6 Research Items
666 Citations
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
2016201720182019202020212022020406080100
Additional affiliations
October 2016 - present
Hochschule Bonn-Rhein-Sieg
Position
  • Researcher
November 2008 - September 2016
Fraunhofer Institute for Algorithms and Scientific Computing SCAI
Position
  • Researcher
April 2004 - November 2008
University of Rostock
Position
  • PhD

Publications

Publications (37)
Chapter
Ionic liquids are highly relevant for industrial applications as they stand out due to their special chemical and physical features, e.g. low vapor pressure, low melting point or extraordinary solution properties. The goal of this work is to study the capability of the three ionic liquids [C2MIM][NTf2], [C12MIM][NTf2] and [C2MIM][EtSO4] to diffuse...
Article
In this contribution, we present two new united-atom force fields (UA-FFs) for 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [Cn MIM][NTf2 ] (n=1, 2, 4, 6, 8) ionic liquids (ILs). One is parametrized manually, and the other is developed with the gradient-based optimization workflow (GROW). By doing so, we wanted to perform a hard te...
Article
Experimental data on the interfacial tension of ionic liquids in CO2 and CH4 atmospheres at elevated pressures (up to 20 MPa and 353 K) are presented and discussed. In addition, molecular modeling is utilized to describe the thermophysical properties under process-relevant conditions. Molecular modeling has the potential to predict findings in orde...
Article
Knowledge about the thermodynamic properties of fluids and their mixtures are fundamental for the design of industrial processes. In the field of tertiary oil and gas production, significant experimental efforts to identify properties of compressed gas mixtures are made worldwide. Often expensive and dangerous high-pressure laboratory methods are...
Article
Full-text available
Der vorliegende Übersichtsartikel berichtet über Fortschritte in der molekularen Modellierung und Simulation mittels massiv-paralleler Hoch- und Höchstleistungsrechner (HPC). Im SkaSim-Projekt arbeiteten dazu Partner aus der HPC-Community mit Anwendern aus Wissenschaft und Industrie zusammen. Ziel dabei war es mittels HPC-Methoden die Vorhersage vo...
Article
Full-text available
Molecular simulations are an important tool in the study of aqueous salt solutions. To predict the physical properties accurately and reliably, the molecular models must be tailored to reproduce experimental data. In this work, a combination of recent global and local optimization tools is used to derive force fields for MgCl2 (aq) and CaCl2 (aq)....
Article
Full-text available
In this work, different global optimization techniques are assessed for the automated development of molecular force fields, as used in molecular dynamics and Monte Carlo simulations. The quest of finding suitable force field parameters is treated as a mathematical minimization problem. Intricate problem characteristics such as extremely costly and...
Conference Paper
Full-text available
Generally molecular dynamics simulations require the adaptation of different atom or molecular models to desired physcial or chemical properties. In this procedure the appropriate choice of force fields and of corresponding parameters is a crucial issue. In recent years, we developed modular program packages, which can be simply tuned to the diff...
Article
Abstract We have studied the structure and stability of H3O+(H2O)8 clusters using a combination of molecular dynamics sampling and high-level ab initio calculations. 20 distinct oxygen frameworks are found within 2 kcal/mol of the electronic or standard Gibbs free energy minimum. The impact of quantum zero-point vibrational corrections on the relat...
Article
The partition coefficient of a substance measures its solubility in octanol compared to water, and is widely used to estimate toxicity. If a substance is hardly soluble in octanol, it is practically impossible for it to enter (human) cells, and therefore is less likely to be toxic. On the other hand, for novel drugs it might be important to penetra...
Article
We have studied the electrical conductivity of mixtures of the ionic liquid (IL) [C(2)mim][NTf(2)] with chloroform for various concentrations at a temperature of 303 K by both experiments and MD simulations. The molar conductivities exhibit an initial increase with decreasing IL concentration, which again sharply decreases in the region of highly d...
Article
Full-text available
In the framework of the Industrial Fluid Properties Simulation Challenge 2010, liquid–liquid equilibria of dipropylene glycol dimethyl ether and water are determined by molecular dynamics simulation. A new force field for the ether was developed and combined with a water model from the literature (TIP4P/2005). According to the specifications of the...
Article
Full-text available
In this study, the recently developed gradient-based optimisation workflow for the automated development of molecular models is for the first time applied to the parameterisation of force fields for molecular dynamics simulations. As a proof-ofconcept, two small molecules (benzene and phosgene) are considered. In order to optimise the underlying in...
Article
Full-text available
The concept, issues of implementation and file formats of the GRadient-based Optimization Workflow for the Automated Development of Molecular Models ‘GROW’ (version 1.0) software tool are described. It enables users to perform automated optimizations of force field parameters for atomistic molecular simulations by an iterative, gradient-based optim...
Conference Paper
Nowadays, molecular simulations are widely used to support the development process for new materials. Through simulations researchers are capable of predicting general trends quite well. But the key to quantitatively correct property predictions is the accuracy of a simulation's foundation, the force field. A force field describes the intra- and in...
Article
Symbiosis: Far-infrared spectra can be used to check the quality of force fields for molecular dynamics simulations of ionic liquids. On the other hand, MD simulations can explain the molecular basis of measured properties for this new liquid material (see picture).
Article
Stokes-Einstein (SE) and Stokes-Einstein-Debye (SED) relations in the neat ionic liquid (IL) [C(2)mim][NTf(2)] and IL/chloroform mixtures are studied by means of molecular dynamics (MD) simulations. For this purpose, we simulate the translational diffusion coefficients of the cations and anions, the rotational correlation times of the C(2)--H bond...
Article
Full-text available
Ionische Flüssigkeiten (ILs) sind semi-organische Salze, die für gewöhnlich aus einem voluminösen, unsymmetrischen, organischen Kation und einem ebenfalls voluminösen, anorganischen Anion bestehen. Sie zeichnen sich durch sehr interessante strukturelle, dynamische und thermodynamische Eigenschaften aus. So besitzen sie z.B. einen niedrigen Schmelzp...
Article
Full-text available
We report results of molecular dynamics simulations characterizing the solvation and interaction of small apolar particles such as methane and xenon in imidazolium-based ionic liquids (ILs). The simulations are able to reproduce semiquantitatively the anomalous temperature dependence of the solubility of apolar particles in the infinite dilution re...
Article
We calculate the heats of vaporisation for imidazolium-based ionic liquids [C(n)mim][NTf(2)] with n=1, 2, 4, 6, 8 by means of molecular dynamics (MD) simulations and discuss their behavior with respect to temperature and the alkyl chain length. We use a force field developed recently. The different cohesive energies contributing to the overall heat...
Article
Full-text available
The parameterization of a new force-field and its validation for the liquid description of five imidazolium-based ionic liquids [C(n)mim][NTf2] (n=1,2,4,6,8) are described. The proposed force-field is derived to reproduce densities, self-diffusion coefficients for cations and ions as well as NMR rotational correlation times for cations and water mo...
Article
With a combination of FTIR and ab initio calculations we studied the structure of water molecules confined in ionic liquids (ILs). Most of the single water molecules are H-bonded in double donor (DD) configurations either to one anion or to two anions in a 1:2 complex. We show that the vibrational stretching modes of such water molecules can be use...
Article
The structures and ion-pair formation in the ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide are studied by a combination of FTIR measurements and DFT calculations. We could clearly distinguish imidazolium cations that are completely H-bonded to anions from those that are single H-bonded in ion pairs. Ion-pair format...
Article
Wassermoleküle sind empfindliche Sonden zur Bestimmung der Polarität ionischer Flüssigkeiten (ILs). Mit FTIR-Spektroskopie und DFT-Rechnungen wird zunächst die Assoziation der Wassermoleküle in ILs untersucht (Bild: mögliche Konfiguration von H2O in 1-Ethyl-3-methylimidazoliumbis(trifluormethylsulfonyl)imid; rot O, weiß H, blau N, schwarz C, gelb S...
Article
Water molecules can be used as a sensitive probe for measuring the polarity of ionic liquids (ILs). A combination of FTIR spectroscopy and DFT calculations was used to determine the molecular state of water in ILs. The picture shows a possible configuration of H2O in 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide (red O, white H, b...
Article
N-methylacetamide (NMA) and water structures in the hydrophobic solvent carbon tetrachloride are studied by simple FTIR spectroscopy. At very low concentrations of NMA and water mainly the monomer species of both systems are present. This is indicated by two NH stretch frequencies of the trans (nu = 3475 cm(-1)) and cis-NMA monomer (nu = 3431 cm(-1...
Article
H-Brücken-gebundene Wassercluster in CCl4 konnten IR-spektroskopisch nachgewiesen werden. Der Vergleich von gemessenen und berechneten Frequenzen sowie die charakteristische Temperaturabhängigkeit der Bandenintensitäten lassen auf die Bildung von cyclischen Clustern bis zum Tetramer schließen (siehe Bild).
Article
And not a drop to drink: Hydrogen-bonded water clusters could be detected in CCl4 by IR spectroscopy. The comparison between measured and calculated frequencies along with the characteristic temperature behavior of band intensities suggests that cyclic clusters are formed up to the tetramer (see picture).

Questions

Question (1)
Question
I get convergence problems when I use the following input:
$CONTRL SCFTYP=MCSCF MPLEVL=2 RUNTYP=optimize UNITS=ANGS
NUMGRD=.T. ICHARG=1 MULT=2 MAXIT=200 ISPHER=1 $END
$SYSTEM MWORDS=5000 MEMDDI=2000 TIMLIM=1300 $END
$BASIS GBASIS=TZV $END
$GUESS GUESS=HCORE $END
$DET NCORE=6 NACT=11 NELS=13 NSTATE=20 $END
$MCSCF MAXIT=2000 $END
$MCQDPT $END
$DATA
O2
C1
Fe 26.0000 0.00000000 0.00000000 0.00000000
$END
Does anyone know a how to enhance the convergence behaviour?

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Projects

Projects (2)
Project
COFFE represents the sum of our past efforts to semi-automatically derive optimized full-atomistic force fields for organic compounds. It includes mathematical optimization strategies as well as code bits like GROW, Wolf2Pack, SpaGROW, or CoSMoS.