Project NMDeRiC – Microscopic approaches to the nonlinear mechanics of driven defect-rich crystals

Basic data

Acronym:
NMDeRiC
Title:
Microscopic approaches to the nonlinear mechanics of driven defect-rich crystals
Duration:
01/04/2019 to 31/03/2022
Abstract / short description:
We will investigate the elastic and plastic properties of hard and soft matter
crystals in the nonlinear and non-equilibrium regime for large stresses and large deformations.
Bringing together three research groups, allows us to consider three different complementary approaches starting from microscopic
principles in order to calculate elastic and transport coefficients of these systems and to derive the macroscopic
equations for elastic, plastic, and transport phenomena in defective crystals. These approaches are (1) statistical
mechanics concepts with projection operators, (2) classical density functional theory, and (3) efficient computer simulations.
It is well known that the
elastic and plastic properties are strongly influenced by dislocations which are topological defects of
the crystal lattice and are highly mobile. However, less is known about the effect on elasticity and transport of
point defects which do not change the lattice structure and which correspond to vacancies, interstitial particles,
or several particles on a single lattice site. While on a macroscopic level standard elastic theories describe
seven modes (sound waves and diffusive heat transport) , two seminal
works by Martin, Parodi, and Pershan and by Fleming and Cohen
have shown already more than forty years ago that there must be an eighth mode which describes
the diffusion of point defects. Little is known about this eighth mode and its coupling to strains
on the microscopic level. Recent interest results from the discovery of crystals with giant defect densities,
where each particle experiences on average close to one defect among its neighbors. For this reason, our project will
mainly focus on point defects and elaborate a microscopic understanding for their diffusive motion and their influence
on the elastic and plastic properties of the material in the nonlinear and the non-equilibrium
regime. We will especially consider soft crystalline materials and cluster crystals which are
defect-rich and are expected to show strong effects.

Involved staff

Managers

Faculty of Science
University of Tübingen
Institute of Applied Physics (IAP)
Department of Physics, Faculty of Science
Institute of Applied Physics (IAP)
Department of Physics, Faculty of Science

Local organizational units

Institute of Applied Physics (IAP)
Department of Physics
Faculty of Science

Funders

Bonn, Nordrhein-Westfalen, Germany
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