Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session S36: Ultrafast Dynamics of Coupled Electrons and Atomic Motions: Experiments and Precise SimulationsInvited
|
Hide Abstracts |
Sponsoring Units: DCOMP Chair: Andre Schleife, University of Illinois at Urbana-Champaign Room: 601/603 |
Thursday, March 5, 2020 11:15AM - 11:51AM |
S36.00001: Terahertz frequency switching in topological Weyl semimetals Invited Speaker: Aaron Lindenberg I will describe femtosecond-resolution crystallographic measurements probing dynamic switching responses driven by terahertz light pulses in topological Weyl semimetals, focusing on the 2D transition metal dichalcogenide WTe2. We describe a new mechanism for driving large amplitude interlayer shear oscillations with ~1% strain amplitudes, leading to a topologically distinct metastable phase. We further show that such shear strain serves as an ultrafast, energy-efficient means to induce more robust, well-separated Weyl points or to annihilate all Weyl points of opposite chirality. I will also discuss new efforts investigating other means for manipulating the topological phase diagram and interlayer stacking of this material through the application of pure electric fields and through doping/intercalation as probed by both optical and transport measurements. This work defines new possibilities for ultrafast manipulation of the topological properties of solids and for the development of new types of topological optoelectronic devices. |
Thursday, March 5, 2020 11:51AM - 12:27PM |
S36.00002: Observables of real-time lattice dynamics in time-dependent density functional theory Invited Speaker: Hannes Huebener I will discuss real-time simulations of lattice vibrations in solids and their signatures in spectroscopy. In particular signatures of electron-phonon coupling in optical and electron spectroscopies have long been used to investigate materials. With the increasing interest in controlling and manipulating materials properties in a non-equilibrium state, such signatures become relevant also in time-resolved measurements. I will discuss how real-time time-dependent density functional calculations can be used to understand spectral features of electron-phonon coupling of driven electronic structure in solids. A useful interpretative tool that emerges from such a treatment is the picture of a dressed electronic structure, which allows to discuss effects in driven systems without referring to perturbation theory. |
Thursday, March 5, 2020 12:27PM - 1:03PM |
S36.00003: Toward Precise Ab Initio Simulations of the Ultrafast Dynamics of Electrons and Phonons Invited Speaker: Marco Bernardi Recent progress in combining density functional theory and related ab initio methods with kinetic equations are enabling spectacular advances in computing carrier dynamics in materials from first principles. We will first review this framework and early ab initio calculations of electron scattering rates and carrier thermalization, and then discuss recent developments. The talk will focus on a numerical approach to evolve in time the coupled Boltzmann transport equations (BTEs) of electrons and phonons, using ab initio electron-phonon and phonon-phonon interactions together with a parallel algorithm to explicitly time step the BTEs. Our approach can simulate the electron and phonon dynamics up to hundreds of picoseconds (with a femtosecond time resolution), and the accuracy of the interactions used in the calculations can be validated by computing transport properties. We show example calculations on graphene and semiconductors, for which we compute carrier cooling rates, mode-resolved phonon dynamics, transient absorption, and time-resolved structural snapshots and diffuse X-ray scattering. We will show how this approach can be extended to include excitons, by discussing calculations of exciton-phonon interactions and real-time exciton dynamics. We will outline code development efforts, open problems and future directions. |
Thursday, March 5, 2020 1:03PM - 1:39PM |
S36.00004: Recent advances in light induced superconductivity Invited Speaker: Andrea Cavalleri I will discuss how coherent electromagnetic radiation at infrared and TeraHertz frequencies can be |
Thursday, March 5, 2020 1:39PM - 2:15PM |
S36.00005: Time-dependent potential energy surfaces from the exact factorization: A predictive first-principles approach to ultra-fast non-adiabatic dynamics Invited Speaker: Eberhard K Gross Some of the most fascinating phenomena in physics and chemistry, such as the process of vision, as well as exciton dynamics in photovoltaic systems involve the coupled motion of electrons and nuclei beyond the adiabatic approximation, i.e. processes not captured by the dynamics on a single Born-Oppenheimer surface. To go beyond the adiabatic approximation is notoriously difficult as one has to start from the full Hamiltonian of interacting electrons and nuclei. We deduce an exact factorization [1] of the full electron-nuclear wave function into a purely nuclear part and a many-electron wave function which parametrically depends on the nuclear configuration and which has the meaning of a conditional probability amplitude. The equations of motion of these two wave functions provide an ideal starting point to develop efficient algorithms for the study non-adiabatic phenomena. The successful prediction of ultrafast laser-induced isomerization processes [2], the description of decoherence [3], calculations of the molecular Berry phase without invoking the Born-Oppenheimer approximation [4] and accurate predictions of vibrational spectroscopy [5], especially dichroism, will demonstrate the power of this new approach. To tackle non-adiabatic phenomena in solids, such as laser-induced phase transitions, the equations of motion of the exact factorization are “density-functionalized” [6], leading to a coupled set of Kohn-Sham equations for electrons and phonons [7]. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700