Contact

Dr. Matthias Posselt
Head Fundamentals and Simulation
m.posseltAthzdr.de
Phone: +49 351 260 - 3279, 2199
Fax: 13279, 3285

Fundamentals and Simulation

In order to get a better understanding of atomic-level dynamics, kinetics and thermodynamics in solids under particle irradiation and/or thermal and mechanical load the project group Fundamentals and Simulation is dealing with atomistic simulations. The main focus is on investigations of iron-based alloys and semiconductor materials.

Research subjects:

  • Thermodynamics and kinetics of defects; Irradiation-induced defect formation
  • Formation and properties of nanoclusters embedded in solids
  • Ion-beam mixing of Si- and Ge-multilayers
  • Epitaxial recrystallization of amorphous Si and Ge layers

Methods:

  • First-Principle Simulations
  • Molecular Dynamics
  • Monte-Carlo Simulations
  • Binary Collision Simulations

Interaction ODS

Figure1: The dominating attractive pair interactions between O, v, Y, Ti, and Cr in a bcc-Fe matrix. The arrow thickness indicates the intensity of the interaction at the corresponding distance (1st neighbor – 1nn, 2nd neighbor – 2nn, etc.) in the underlying simple cubic lattice. If the atomic species are not connected by arrows, their interaction is repulsive (for more details see Posselt et al. 2014)

Al free energy

Figure 2: Vibrational contribution to the free formation energy of an Al atom in bcc-Fe versus temperature (thick lines), and the sum of vibrational and electronic contributions to the free formation energy (thin lines).  The red and blue color denotes results obtained using the equilibrium atomic positions calculated at the ground state under constant volume and zero-pressure (ZP) conditions, respectively. The green line shows data obtained after applying quasi-harmonic corrections to the ZP-based vibrational free energy (for more details see Murali et al. 2015).

 

Recent publications:

D. Murali, M. Posselt,  M. Schiwarth: First-principles calculation of defect free energies: General aspects illustrated in the case of bcc Fe, Phys. Rev. B 92 (2015) 064103

M. Radek, H. Bracht, B. C. Johnson, J. C. McCallum,  M. Posselt, B. Liedke: Atomic transport during solid-phase epitaxial recrystallization of amorphous germanium, Appl. Phys. Lett. 107 (2015) 082112

Roisin A. Kelly, Bartosz Liedke, Stefan Baldauf, Anushka Gangnaik, Subhajit Biswas,Yordan Georgiev, Justin D. Holmes, Matthias Posselt, Nikolay Petkov: Epitaxial Post-Implant Recrystallization in Germanium Nanowires, Cryst. Growth Des.15 ( 2015) 4581

Shengqiang Zhou, Fang Liu, S. Prucnal, Kun Gao, M. Khalid, C. Baehtz, M. Posselt, W. Skorupa, M. Helm: Hyperdoping silicon with selenium: solid vs. liquid phase epitaxy, Sci. Rep. 5 (2015) 8329

A. Götze, S. Makowski, T. Kunze, M. Hübner, H. Zellbeck, V. Weihnacht, A. Leson, E. Beyer, J.-O. Joswig, G. Seifert, G. Abrasonis, M. Posselt, J. Fassbender, S. Gemming, M. Krause: Tetrahedral amorphous carbon coatings for friction reduction of the valve train in internal combustion engines, Advanced Engineering Materials 16 (2014) 1226

M. Posselt, D. Murali, B. K. Panigrahi: Energetics, structure, and composition of nanoclusters in Oxide Dispersion Strengthened Fe-Cr alloys, Modelling Simul. Mater. Sci. Eng. 22 (2014) 085003

M. Radek, H. Bracht, M. Posselt, B. Liedke, B. Schmidt, D. Bougeard: Temperature dependence of ion-beam mixing in crystalline and amorphous germanium isotope multilayer structures, J. Appl. Phys. 115 (2014) 023506

T. Kunze, M. Posselt, S. Gemming, G. Seifert, A. R. Konicek,  R. W. Carpick, L. Pastewka, M. Moseler: Wear, plasticity, and rehybridization in tetrahedral amorphous carbon, Tribol. Lett. 53 (2014) 119

M.Posselt: Importance of configurational contributions to the free energy of nanoclusters, AIP Advances 3 (2013) 072137

M. Talati, M. Posselt, G. Bonny, A. Al-Motasem, F. Bergner: Vibrational contribution to the thermodynamics of nanosized precipitates: vacancy–copper clusters in bcc-Fe, J. Phys.: Condens. Matter 24 (2012) 225402

H. Bracht, M. Radek, R. Kube, S. Knebel, M. Posselt, B. Schmidt, E. Haller, D. Bougeard: Ion-beam mixing in crystalline and amorphous germanium isotope multilayer structures, J. Appl. Phys. 110 (2011) 093502

D. Terentyev, L. Malerba, G. Bonny, A. T. Al-Motasem, M. Posselt: Interaction of an edge dislocation with Cu–Ni-vacancy clusters in bcc iron, J. Nucl. Mater. 419 (2011) 134

A.T. Al-Motasem, M. Posselt, F. Bergner: Nanoclusters in bcc-Fe containing vacancies, copper and nickel: Structure and energetics, J. Nucl. Mater. 418 (2011) 215

A. T. Al-Motasem, M. Posselt, F. Bergner, U. Birkenheuer: Structure, energetics and thermodynamics of copper-vacancy clusters in bcc-Fe: An atomistic study, J. Nucl. Mater. 414 (2011) 161


If you are interested in writing Bachelor, Master, Diploma or Doctoral Theses in this research field, please contact Dr. Matthias Posselt (m.posselt@hzdr.de).


Contact

Dr. Matthias Posselt
Head Fundamentals and Simulation
m.posseltAthzdr.de
Phone: +49 351 260 - 3279, 2199
Fax: 13279, 3285