[Aspuru-Guzik Group List] ITAMP Lunch Seminar (Nov. 9th) - John Sous, University of British Columbia

Speaker: John Sous, (University of British Columbia) Date: Thursday, November 9th Time: 12:00-1:00 pm Includes Pizza. Title: Phonon-mediated repulsion, sharp transitions and (quasi)self-trapping in the extended Peierls-Hubbard model Abstract: Particle-phonon coupling is generically expected to lead to a screening of the bare particle​-​particle interactions. If low-energy overscreening occurs, the resulting attractive interactions are responsible for conventional superconductivity as described by the Bardeen-Cooper​-​Schrieffer theory. ​I will demonstrate that Peierls-type particle-phonon coupling not only leads to an enhanced repulsion between identical fermions/hard-core bosons, but also generates an additional effective interaction not of density-density type and thus not involved in screening. This interaction moves pairs of neighbor particles as a whole; this has unusual consequences such as a (quasi)self-trapping transition for a bound pair even when the individual particles are very mobile. These results open new directions in the study and understanding of the effects of particle-boson coupling, relevant for understanding behavior in Physics, e.g. in quantum materials; Chemistry, e.g. in optoelectronic processes; and Biology, e.g. in photosynthesis and DNA. Location: B-106 @ Center for Astrophysics (60 Garden Street) Directions: After entering the lobby of the CfA, turn right to enter the hallway of the B building. In the hallway, turn right again, B-106 will be at the end of the hallway on the left side.