Electronic structure and atomistic modelling for materials science
The Applied Physics group at LTU was established in Feb. 2013 by the applicant Andreas Larsson, and has joined forces with the group of applicant Sven Öberg. We are a part of the Division of Materials Science, and we study the properties materials and their interfaces using both electronic structure- and atomistic modelling. The materials development in the information society is constantly moving in the direction of thinner layers and nanostructured materials, and measurements at smaller scales, in what is termed as nanotechnology. In this regime information on the atomic scale is desirable and necessary, since atomic and molecular scale properties and processes govern material properties and their interactions. We model material properties on two levels of theory: electronic structure theory and atomistic theory, such as molecular mechanics molecular dynamics (MM-MD) and spin dynamics, where the atom is the smallest building block. The modelling with these theories completes each other where quantum mechanics based on density functional theory (DFT) is used to model hundreds (up to thousands) of atoms in processes that make and break chemical bonds, while MM-MD and spin dynamics is used to study the dynamics of millions of atoms for several nanoseconds. These two theories are complimented with quantum mechanical molecular dynamics (QMD) that is used for the study of dynamic processes where chemical bonds are reformed. To describe the materials within this proposal it is often necessary to describe the quantum mechanical nature beyond the state-of-the-art method DFT, specifically with inclusion of relativistic effects, explicit electron correlation, and with the inclusion of proper description of van der Waals interactions between molecules and material surfaces. The inclusion of these effects adds another level of complexity to the simulations, rendering them even more time-consuming. As a particular strength of the group’s efforts with regard to MM-MD and spin dynamics is that we extract parameters from our first principles electronic structure simulations to improve the description using the atomistic theories. In this way we are able to do very precise predictions also from these empirical models. Our aim is always to make either predictive modelling of as yet studied systems and phenomena, and/or to make use of the empirical simulations to suggest new uses and developments of these newly described systems and effects. For this work to continue successfully we need ample computer resources.