Atomistic Modelling and Simulation (AMS)
|Prof. Dr. Ralf Drautz|
|Within the modelling activities of the three ICAMS Departments, the department of Atomistic Modelling and Simulation works on the finest, most fundamental length scale of atomistic simulations. Our research has two main objectives: 1. to obtain effective interatomic interactions from fundamental theories of the electronic structure, 2. to employ the effective interatomic interactions in large scale and long time atomistic simulations and in this way obtain effective parameters that may serve as input for the modelling activities in the two other ICAMS departments. Effective interatomic interactions are obtained by systematically coarse graining the electronic structure at two levels of approximation. In a first step, the electronic structure is simplified to the tight-binding approximation by a second-order perturbation expansion of density functional theory in a minimal basis representation. Work at this level of coarse graining is carried out in close collaboration with the ASG Modelling. In a second step, bond-order potentials are derived as an analytic approximation to the exact solution of the tight-binding model. The analytic bond-order potentials are developed in close collaboration with Professor David Pettifor, Oxford.|
|The bond-order potentials are then used in large scale and long time atomistic simulation of the structural stability and the mechanical response of a material or for analyzing the kinetics of a phase transformation. In this way a coherent link from the electronic structure to the continuum description of materials on the meso- and macroscale is obtained. As effective interatomic interactions may be derived for a wide variety of elements, interatomic potentials may be generated for transition metals and their alloys as well as semiconductors and sp-valent materials, including the effects of charge transfer and magnetism. High-throughput density functional calculations are used to explore the chemical phase space of binary and ternary compounds and to validate trends in structural stability that are predicted by the simplified models of the electronic structure and the bond-order potentials. The high-throughput density functional simulations also help to improve and re-parameterize thermodynamic databases.|
Three research groups represent the department‘s focus on establishing a coherent link from the electronic structure through atomistic simulations to meso- and macroscopical modelling hierarchies.
A list of research projects currently offered in the department of Atomistic Modelling and Simulation (Prof. Drautz) can be found here.