【NCTS Activity】Molecular Berry curvature for lattice dynamics
Speaker：Prof. Qian Niu (University of Science and Technology of China)
Time：2023/01/11 (Wed.) 14:00
Place：Lecture Hall, 4F, Chee-Chun Leung Cosmology Hall, NTU (Hybrid)
Online meeting link：https://nationaltaiwanuniversity-zbh.my.webex.com/nationaltaiwanuniversity-zbh.my/j.php?MTID=mead121b2cf907c9930c3a8a73eefbcfb
Abstract：
Many phonon properties, such as angular momentum and Hall effect,
depend crucially on the absence of time reversal symmetry in lattice dynamics.
This could directly originate from an applied magnetic field acting upon the ionic charges,
or indirectly through electrons in terms of a molecular Berry curvature acting as a vector potential.
We demonstrate in a concrete model how this Berry curvature can arise, how optical modes are split
into ones with different chirality, and how acoustic modes can acquire non-reciprocity by additionally
breaking spatial inversion symmetry.