Atomic Scale Modeling of Alloys and Functional Materials
I. Understanding and manipulating the electrical and thermal conductivity of materials is of interest to a large number of applications, including electronic and optoelectronic devices, thermal management, and thermoelectric energy generation. In collaboration with several experimental groups, we are studying the electrical and thermal conductivity of various materials and their dependence on microstructure. In this context we plan to continue our investigations regarding the electronic and vibrational structure of inorganic clathrates and chalcogenides [see e.g., our recent publications in Chemistry of Materials [doi:10.1021/acs.chemmater.6b02117 (09/2016)] and Physical Review B [doi:10.1103/PhysRevB.94.115205 (09/2016)]. To this end, we use both first-principles calculations and semi-empirical models in combination with solvers for the Boltzmann transport equation as well as molecular dynamics 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. Density functional theory (DFT) calculations are conducted using the VASP and GPAW codes. Boltzmann transport calculations are carried out using phono3py, shengBTE, and boltzTrap. Molecular dynamics simulations are conducted using LAMMPS. We will also employ in-house model construction codes (atomicrex and iceT). This research is supported by a Fellowship grant from the Knut and Alice Wallenberg foundation. II. Metallic nanoparticles are key components in many areas including e.g., catalysis, medicine, energy generation and storage. The properties of these particles are highly sensitive to variations in size, shape, composition and surface termination. Recently, owing to fascinating advances in shape-selected nanocrystal synthesis, particles with well-controlled size, shape and chemical composition have become available. This has brought about new exciting opportunities for engineering particle properties. Here, 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. The specific objectives are * to quantitatively resolve the phase diagrams of nanoparticles composed of late transition-metals as a function of size, shape, and surface chemistry, and * to predict plasmonic properties as a function of size, shape, composition, and chemical state under experimentally relevant conditions. In this subproject we will primarily employ DFT calculations as available in the GPAW and VASP codes. Post-processing and model building as described above will be carried out as well. This project is supported by a project grant from the Swedish Research Council and will be carried out in collaboration with Dr. Mikael Kuisma at the University of Jyväskylä, Finland. Note: Compared to the previous two years, we kindly ask for an increase of our allocation from 130k to 200k core hours per month, since our group has grown significantly and currently includes six PhD students and one post-doc.