"Recent Advances in First-Principles Materials Modeling: van der Waals Forces and NMR Chemical Shifts in Density Functional Theory"
Timo Thonhauser, Wake Forest University
I will give an introduction to recent advances in first-principles materials modeling, discussing two new approaches. First I will address a shortcoming of standard density functional theory, which gives poor results for materials with van der Waals interactions. To remedy the situation, I will introduce an exchange-correlation functional that includes van der Waals interactions in a seamless manner. The main advantage of our approach is the much more favorable scaling of the computational expense compared to standard quantum-chemistry approaches. Second, I will present an approach to derive a fully quantum-mechanical theory for the orbital magnetization in extended materials and, subsequently, a novel way to calculate NMR chemical shieldings based on this new theory. Instead of obtaining the shieldings from the response to an external magnetic field, we derive it directly from the orbital magnetization appearing in response to a microscopic magnetic dipole. Throughout this colloquium I will show applications of both approaches to a variety of materials of current interest such as water, DNA, clathrates, and hydrogen-storage materials.
Timo Thonhauser received his PhD in solid-state physics from the Institute for Theoretical Physics at Austria's University of Graz in 2001. He subsequently held postdoc positions in physics at Penn State and Rutgers, followed by a research associate position in materials science and engineering at MIT. He joined the Department of Physics at Wake Forest University in 2008. His research is devoted to the application of condensed-matter theory to outstanding problems in physics, biophysics, chemistry and materials science, with applications to nano-, bio- and energy-related materials.