Title:	Atomic Scale Modeling of Alloys and Functional Materials
DNr:	SNIC 2015/1-285
Project Type:	SNIC Medium Compute
Principal Investigator:	Paul Erhart <erhart@chalmers.se>
Affiliation:	Chalmers tekniska högskola
Duration:	2015-09-28 – 2016-10-01
Classification:	10304
Homepage:	http://fy.chalmers.se/~erhart
Keywords:

Abstract

I. Understanding and manipulating the thermal conductivity of materials is of interest to a large number of applications, including thermal management, thermoelectric energy generation and active cooling. In collaboration with experimental groups at Chalmers we are studying the thermal conductivity of various materials and its dependence on microstructure with an emphasis on thermoelectrics. This research is supported by a Fellowship grant from the Knut and Alice Wallenberg foundation awarded in December 2014. In this context we plan to continue our investigations regarding the electronic and vibrational (phononic) structure of for example inorganic clathrates, silicides, selenides, and sulfides [see e.g., our recent publication in Chemistry of Materials, doi:10.1021/acs.chemmater.5b01509]. To this end, we will use both first-principles calculations and as semi-empirical models in combination with solvers for the Boltzmann transport equation as well as direct atomistic simulations. The computational expense of individual calculations, the large number of degrees of freedom to be treated, and the chemical complexity of the systems of interest imply that we will require very substantial computational resources in order to complete our research plan. The codes to be used are all well suited for massively parallel computing environments. In particular, we will employ an in-house C++ based code, which supports optimization algorithms (e.g., parallel tempering) that can readily take advantage of parallel resources. II. Metallic alloys are highly versatile materials with applications in almost every area of modern technology. Their properties are strongly dependent on the internal structure of the material and can be modified dramatically both by heat and mechanical treatments. Our research is concerned with the development of models and tools for simulating concentrated multi-component alloys on the atomic scale. This approach enables an improved understanding of the microscopic processes that govern materials response on the macroscopic scale. Specifically we target W-based alloys with respect to applications in fusion reactors. In particular, we plan to continue our investigation of the effect of alloying on screw dislocation climb, which is critical for understanding plastic deformation behavior and preventing catastrophic failure due to brittle fracture. This project is carried out in collaboration with Prof. Marian at the University of California, Los Angeles and Dr. Stukowski at Technische Universität Darmstadt. We will also study the oxidation behavior of these materials in close collaboration with the experimental group of Prof. Linsmeier at Forschungszentrum Jülich. The oxidation behavior of these materials is crucial for the intended application of W-based alloys in fusion reactors; the rapid exposure of the reactor core to air (e.g., in the case of an accident) can namely present a safety hazard, if the amount of heat that is released during the oxidation process causes mechanical failure of the structural components. Note: Compared to the previous two years, we kindly ask for an increase of our allocation from 100k to 150k core hours per month, since our group has grown significantly and currently includes four PhD students and one post-doc.