Ceresoli, Davide

Thursday Oct 10, 2013
Time: 11:00
Place: ETH Science City, HPF G6
Host: Alexey A. Soluyanov / Matthias Troyer

The orbital magnetization in periodic systems: theory and ab-initio calculations

Davide Ceresoli
University of Milan, Italy

The electric polarization (P) and the orbital magnetization (M) are well known textbook topics in solid state physics. While it is easy to compute their derivatives in an extended system, P and M themselves are not easy to formulate, due to the unboundedness of the position operator. The problem of the electric polarization has been solved in the '90s by the Modern Theory of Polarization, which relates the electric polarization to the electrons Berry phase. Only recently, two independent groups found a formula for the orbital magnetization in periodic systems.  I will briefly review our derivation, which is based on Wannier functions, and I will present first principles calculations of the orbital magnetization by the plane wave pseudopotential method. As an application, I will show that the NMR chemical shifts and the EPR g-tensor can be calculated from the orbital magnetization by a "converse" approach.  The advantages of the new approach are: (1) it avoids any linear response calculation, (2) it is not plagued by the gauge-origin problem of most quantum chemistry methods.