Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session M60: First-Principles Simulations of Excited-State Phenomena: Out-of-Equilibrium DynamicsFocus
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Sponsoring Units: DCOMP Chair: Emmanouil Kioupakis, University of Michigan Room: Room 419 |
Wednesday, March 8, 2023 8:00AM - 8:36AM |
M60.00001: A first principles QEDFT perspective on light-driven non-equilibrium phenomena in quantum materials Invited Speaker: Angel Rubio We provide an overview of how well-established concepts in the fields of quantum chemistry and materials have to be adapted when the quantum nature of light becomes important. We will pursue the question whether it is possible to create these new states of materials as groundstates of the system. To this end we will show how the emerging (vacuum) dressed states resembles Floquet states in driven systems. A particular appeal of light dressing is the possibility to engineer symmetry breaking which can lead to novel properties of materials. Strong light–matter coupling in cavities provides a pathway to break fundamental materials symmetries, like time-reversal symmetry in chiral cavities. We will discuss the potential to realize non-equilibrium states of matter that have so far been only accessible in ultrafast and ultrastrong laser-driven materials. We illustrate the realization of those ideas in molecular complexes and 2D materials and show that the combination of cavity-QED and 2D twisted van der Waals heterostructures provides a novel and unique platform for the seamless realization of a plethora of interacting quantum phenomena, including exotic and elusive correlated and topological phases of matter. We will briefly introduce our newly developed quantum electrodynamics density-functional formalism (QEDFT) as a first principles framework to predict, characterize and control the spontaneous appearance of ordered phases of strongly interacting light-matter hybrids. |
Wednesday, March 8, 2023 8:36AM - 8:48AM |
M60.00002: Many-body excitonic picture of ultrafast photoexcited dynamics in van der Waals heterostructures CHEN HU, Mit H Naik, Yang-Hao Chan, Steven G Louie Ultrafast optical dynamics in transition metal dichalcogenide (TMD) heterobilayers is of fundamental scientific interest and importance for potential optoelectronics applications. Despite much progress in experiment measurements, their theoretical interpretations remain basically at an insufficient level. A full understanding of this phenomenon requires accurate descriptions of both nonequilibrium dynamics and many-body excitonic physics. In this work, based on our first-principles time-dependent adiabatic GW approach [1], we propose a new many-body excitonic mechanism for the dynamics of converting photoexcited intralayer to interlayer excitations and the associated ultrafast optical responses in TMD heterobilayers. We find that nonlocal couplings between the intralayer and interlayer exciton states (i.e., two-particle correlated electron-hole pairs) dominate the ultrafast optical response, conceptually different from the previously-believed single-particle picture of independent charge transfer between layers. Strong excitonic effects (electron-hole interactions) are discovered to be the main driving force for real-time evolution of the photo-excitations, and play a crucial role on the ultrafast pump-probe optical responses by enhancing the probed optical signal by over one-order of magnitude with a rising time of about 300 femtoseconds, in good agreement with experiments. |
Wednesday, March 8, 2023 8:48AM - 9:00AM |
M60.00003: Full minimal coupling in the self-consistent Maxwell-TDDFT first principles framework Franco P Bonafe, Heiko Appel, Angel Rubio In the realm of quantum chemistry and materials science, the dipole approximation (DA) is by far the most widely used treatment of light-matter coupling, owing to the typically longer wavelength of light compared to the size of the matter system. However, in many relevant situations, in particular dealing with nanoplasmonics and non-equilibrium quantum matter, local fields arise upon interaction with external fields, with spatial features that can be no longer be considered in the long wavelength limit. Moreover, core level spectroscopies which demand UV or x-ray pulses cannot be treated within this approximation either. Going beyond the DA to properly account for the self-induced fields is then relevant, but their theoretical treatment is challenging. |
Wednesday, March 8, 2023 9:00AM - 9:12AM |
M60.00004: Modelling hot-carrier generation in metallic nanoparticles containing more than one million atoms Johannes C Lischner Energetic or "hot" electrons and holes are generated in metallic nanoparticles from the decay of localized surface plasmons. These carriers can be used for applications in photocatalyis or sensing. A detailed understanding of the relationship between hot-carrier properties and the composition, shape, environment and size of metallic nanoparticles is needed to guide experimental efforts towards highly efficient hot-carrier devices. However, the modelling of experimentally relevant nanoparticles is challenging because of their large sizes often containing millions of atoms rendering standard electronic structure techniques, such as those based on first-principles density-functional theory, unfeasible. To overcome this challenge, I will introduce a new material-specific quantum-mechanical modelling approach that combines ab-initio derived tight-binding models with solutions of Maxwell's equations for the nanoparticle. To evaluate Fermi's golden rule for the localized surface plasmon decay for large nanoparticles, we employ a decomposition in terms of Chebychev polynomials combined with highly efficient stochastic trace evaluations. The resulting approach allows us to study hot-carrier generation in large nanoparticles of Au, Ag and Cu and understand the interplay of interband and intraband transitions as function of the nanoparticle size. In addition, results for hybrid nanparticles consisting of both plasmonic and catalytic metals will be discussed including core-shell architectures or satellite systems. |
Wednesday, March 8, 2023 9:12AM - 9:24AM |
M60.00005: Plasmon Excitation and Decay in Metallic Nano-particle at Semiconductor Surface: RT-TDDFT simulation John L Bost, Christopher C Shepard, Yosuke Kanai We employ real-time time-dependent density functional theory (RT-TDDFT) to study the process of plasmon-induced charge transfer from a plasmonic metal nanoparticle to semiconductor surface at the interface. Using the recently-developed approach of propagating maximally-localized Wannier functions in RT-TDDFT, we describe out-of-equilibrium dynamics of the plasmon in the nano-particle and the resulting effect at the interface. In this work we focus specifically on the plasmonic Ag20 nanocluster interfaced with a hydrogenated silicon surface. We will discuss how the decay of plasmon excitation results in the energy transfer to the semiconductor. |
Wednesday, March 8, 2023 9:24AM - 9:36AM |
M60.00006: Accelerating Hybrid XC in RT-TDDFT using Maximally-localized Wannier functions Thomas Carney, Christopher C Shepard, Yosuke Kanai The use of accurate exchange-correlation (XC) functionals with the exact exchange greatly enhances our ability to model the electron dynamics in complicated systems using real-time time-dependent density functional theory (RT-TDDFT). However, the computational cost of hybrid XC can be extremely large particularly for condensed phase systems, being often more than two orders of magnitude larger than that of using standard GGA approximations. Such a large computational cost becomes prohibitive especially in RT-TDDFT simulation. Building on our recent work on propagating maximally-localized Wannier functions (MLWFs) in RT-TDDFT, we discuss our effort on significantly reducing the cost of the exact exchange evaluation for hybrid XC. For insulating systems, time-dependent MLWFs remain spatially localized, and the computational cost can be reduced by as much as one order of magnitude without compromising the accuracy. We will discuss a few examples for demonstrating this methodology using the plane-wave pseudopotential implementation of RT-TDDFT. |
Wednesday, March 8, 2023 9:36AM - 9:48AM |
M60.00007: Real-time observation of Berry curvature and nonlinear Hall effect in insulators MAHMUT S OKYAY, MIN CHOI, Bryan M Wong Berry curvature is the key component for various geometric properties of energy bands in many solid-state systems, such as the topological invariance of linear Hall conductivity with broken time-reversal symmetry [1]. Beyond the linear response, the nonlinear Hall effect of time-reversal symmetric materials has attracted significant interest in the last decade [2]. Here, we propose a real-time propagation framework of Bloch wavefunctions to observe linear and nonlinear Hall currents. Together with perturbation analysis of the theoretical Hamiltonian models, we performed real-time time-dependent density functional theory (rt-TDDFT) calculations to investigate an insulator’s first- and second-order optical responses. We show that the topological nature of Bloch states is directly reflected in the real-time responses. Moreover, our implementation is capable of reproducing perturbative second harmonic generation (SHG) spectra [3], polarization anisotropy of SHG signals, and intensity dependence on high harmonic generation for a nonlinear Hall response. We present an rt-TDDFT method that can analyze the band geometry of solid states through real-time simulations of linear and nonlinear optical Hall effects. |
Wednesday, March 8, 2023 9:48AM - 10:00AM |
M60.00008: Anisotropic carrier dynamics in a laser-excited Fe/(MgO)(001) heterostructure from real-time time-dependent DFT Rossitza Pentcheva, Elaheh Shomali, Markus E Gruner The interaction of a femtosecond optical pulse with a metal/oxide interface is addressed in the framework of time-dependent density functional theory (TDDFT) in the real-time domain using the Elk code. In particular, we systematically investigate the layer-resolved dynamics of the electronic excitations in a Fe1/(MgO)3(001) heterostructure as a function of laser frequency, peak power density and polarization direction [1,2]. We find a marked anisotropy in the response to in- and out-of-plane polarized light, which changes its character qualitatively depending on the excitation energy: the Fe-layer is efficiently addressed at low frequencies by in-plane polarized light, whereas for frequencies higher than the MgO band gap, we find a particularly large response of the MgO-layers for cross-plane polarized light. This points towards a path to selectively manipulate the excitation dynamics pattern in anisotropic systems. Moreover, the hybridized states at the interface play an essential role, as they mediate concernted transitions from the valence band of MgO into the 3d states of Fe closely above the Fermi-level and transitions from the Fe-states below the Fermi level into the conduction band of MgO. As these transitions occur simultaneously without altering the charge balance of the layers, they could potentially lead to an efficient transfer of excited carriers into the MgO bulk, with the corresponding electron and hole states separated by a significantly larger energy than the photon energy. |
Wednesday, March 8, 2023 10:00AM - 10:12AM |
M60.00009: Using Real-time TDDFT in the Plane-wave Pseudopotential Formulation to Study High Energy Ion Irradiation in solvated DNA Christopher C Shepard, Yosuke Kanai, Dillon C Yost Understanding the electronic excitation response of DNA to charged particle radiation, such as high-energy protons, α-particles and carbon ions, has become increasingly important, particularly with recent advances in ion-beam cancer therapy. Unlike photons, high-energy ions show a highly localized energy deposition profile and can more precisely target tumor cells without damaging surrounding healthy cells. However, how protons and α-particles induce DNA damage is not understood at the molecular level. Here we use the Qb@ll/Qbox code and real-time time-dependent density functional theory (RT-TDDT) in the Plane-wave Pseudopotential Formulation to simulate the non-equilibrium energy transfer excitation in solvated DNA under ion irradiation1. In particular, we discuss how propagation of the maximally-localized Wannier functions (MLWFs) can provide key insights at the molecular-level. Our results show significantly more energy is deposited onto the sugar-phosphate side chains, generating highly energetic holes and likely causing strand damage. |
Wednesday, March 8, 2023 10:12AM - 10:24AM |
M60.00010: Massively Parallelized Real-Time Propagation via Plane-wave based Time-Dependent Density Functional Theory MIN CHOI, Bryan M Wong The real-time time-dependent density functional theory (rt-TDDFT) is an attractive model for simulating and calculating quantum dynamics properties such as the optical absorption spectrum. Several developments and applications in this field have been achieved in recent years. However, rt-TDDFT calculations require substantial computation resources. Applying rt-TDDFT to increasingly large systems requires developing methods to overcome computational bottlenecks, one being the cost needed to form the time propagator for the RT-TDDFT equations. |
Wednesday, March 8, 2023 10:24AM - 10:36AM |
M60.00011: Quantum Dynamics in a Double-Well Potential Using Quasiclassical Methods Nicole H Drew The quartic double-well potential has been used to model a variety of physical systems due to its simple form that permits straightforward realization and analysis. In this work, we investigate the dynamics of non-equilibrium quantum states in one-dimensional double wells using nonstandard “quasiclassical” techniques that treat a wave packet’s average position and standard deviation on equal footing in an effective potential landscape while incorporating Heisenberg’s uncertainty principle. In this talk, we will outline the theory of the quasiclassical method, apply this method to find oscillation frequencies of states hosted in the double well, compare these results to those computed using the standard Schrödinger equation, and discuss the relative advantages or drawbacks of these two techniques. |
Wednesday, March 8, 2023 10:36AM - 10:48AM |
M60.00012: INQ: reinventing the electronic-structure code Xavier Andrade In the last few years we have seen a radical change in the design of HPC systems. |
Wednesday, March 8, 2023 10:48AM - 11:00AM Author not Attending |
M60.00013: Functionals, excited-states and photonic environments of strongly coupled light-matter systems Johannes Flick Recent experiments at the interface of quantum optics and chemistry have realized altered materials properties using strong light-matter coupling. To describe this regime, electronic structure methods have been extended to capture strongly-coupled light-matter systems from first principles. In this talk, I give an overview on recent developments of the ab initio methods for strongly coupled light-matter systems, quantum-electrodynamical density-functional theory (QEDFT), cavity Born-Oppenheimer approximation (CBOA) and polaritonic coupled-cluster theory. This discussion includes the search for computationally efficient density functionals for QEDFT [1], pathways to improve their accuracy, as well as extensions of linear-reponse theories to include realistic electromagnetic environments via multi-mode setups and macroscopic QED. |
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