2024 New's Items

Equivariant Neural Networks Utilizing Molecular Clusters for Accurate Molecular Crystal Lattice Energy Predictions

Gupta K
Stulajter MM
Shaidu Y
Neaton JB
de Jong WA
2024

Equivariant neural networks have emerged as prominent models in advancing the construction of interatomic potentials due to their remarkable data efficiency and generalization capabilities for out-of-distribution data. Here, we expand the utility of these networks to the prediction of crystal structures consisting of organic molecules. Traditional methods for computing crystal structure properties, such as plane-wave quantum chemical methods based on density functional theory (DFT), are prohibitively resource-intensive, often necessitating compromises in accuracy and the choice of...

Dark Metastable Conduction Channels near a Metal-Insulator Transition

Devidas TR
Reichanadter JT
Haley SC
Sterenberg M
Moore JE
Neaton JB
Analytis JG
Kalisky B
Maniv E
2024

Materials that transition between metal and insulator, the two main states that distinguish all solids, are fascinating because they underlie many mysteries at the frontier of solid state physics. In 1T-TaS22, the metal-insulator transition is linked to a metastable hidden state arising within a chiral charge density wave (CDW) whose basic nature remains an open question. In this work, we show that pulses of current through these...

Rearrangement collision theory of phonon-driven exciton dissociation

Coveney CJN
Haber JB
Alvertis AM
Neaton JB
Filip MR
2024

Understanding the processes governing the dissociation of excitons to free charge carriers in semiconductors and insulators is of central importance for photovoltaic applications. Dyson's S-matrix formalism provides a framework for computing scattering rates between quasiparticle states derived from the same underlying Hamiltonian, often reducing to familiar Fermi's “golden rule” like expressions at first order. By presenting a rigorous formalism for multichannel scattering, we extend this approach to describe scattering between composite quasiparticles and, in particular, the process of...

Phonon-Driven Femtosecond Dynamics of Excitons in Crystalline Pentacene from First Principles

Cohen G
Haber JB
Neaton JB
Qiu DY
Refaely-Abramson S
2024

Nonradiative exciton relaxation processes are critical for energy transduction and transport in optoelectronic materials, but how these processes are connected to the underlying crystal structure and the associated electron, exciton, and phonon band structures, as well as the interactions of all these particles, is challenging to understand. Here, we present a first-principles study of exciton-phonon relaxation pathways in pentacene, a paradigmatic molecular crystal and optoelectronic semiconductor. We compute the momentum- and band-resolved exciton-phonon interactions, and use them...

Exciton–Phonon Coupling Induces a New Pathway for Ultrafast Intralayer-to-Interlayer Exciton Transition and Interlayer Charge Transfer in WS2–MoS2 Heterostructure: A First-Principles Study

Chan Y
Naik MH
Haber JB
Neaton JB
Louie SG
Qiu DY
da Jornada FH
2024

Despite the weak, van der Waals interlayer coupling, photoinduced charge transfer vertically across atomically thin interfaces can occur within surprisingly fast, sub-50 fs time scales. An early theoretical understanding of charge transfer is based on a noninteracting picture, neglecting excitonic effects that dominate optical properties of such materials. We employ an ab initio many-body perturbation theory approach, which explicitly accounts for the excitons and phonons in the heterostructure. Our large-scale first-principles calculations directly probe the role of exciton–phonon...

Strongly Bound Excitons and Anisotropic Linear Absorption in Monolayer Graphullerene

Champagne A
Camarasa-Gómez M
Ricci F
Kronik L
Neaton JB
2024

Graphullerene is a novel two-dimensional carbon allotrope with unique optoelectronic properties. Despite significant experimental characterization and prior density functional theory calculations, unanswered questions remain as to the nature, energy, and intensity of the electronic and optical excitations. Here, we present first-principles calculations of the quasiparticle band structure, neutral excitations, and absorption spectra of monolayer graphullerene and bulk graphullerite, employing the GW–Bethe–Salpeter equation (GW-BSE) approach. We show that strongly bound excitons dominate the...

Excitations in layered materials from a non-empirical Wannier-localized optimally-tuned screened range-separated hybrid functional

Camarasa-Gómez M
Gant SE
Ohad G
Neaton JB
Ramasubramaniam A
Kronik L
2024

Accurate prediction of electronic and optical excitations in van der Waals (vdW) materials is a long-standing challenge for density functional theory. The recent Wannier-localized optimally-tuned screened range-separated hybrid (WOT-SRSH) functional has proven successful in non-empirical determination of electronic band gaps and optical absorption spectra for covalent and ionic crystals. However, for vdW materials the tuning of the material- and structure-dependent functional parameters has only been attained semi-empirically. Here, we present a non-empirical WOT-SRSH approach applicable...

Influence of Electronic Correlations on Electron–Phonon Interactions of Molecular Systems with the GW and Coupled Cluster Methods

Alvertis M
Williams-Young DB
Bruneval F
Neaton JB
2024

Electron–phonon interactions are of great importance to a variety of physical phenomena, and their accurate description is an important goal for first-principles calculations. Isolated examples of materials and molecular systems have emerged where electron–phonon coupling is enhanced over density functional theory (DFT) when using the Green’s-function-based ab initio GW method, which provides a more accurate description of electronic correlations. It is, however, unclear how general this enhancement is and how employing high-end quantum chemistry methods, which further improve the...

Chern dartboard insulator: sub-Brillouin zone topology and skyrmion multipoles

Chen Y-C
Lin Y-P
Kao Y-J
2024

Topology plays a crucial role in many physical systems, leading to interesting states at the surface. A paradigmatic example is the Chern number defined in the Brillouin zone that leads to robust gapless edge states. Here we introduce the reduced Chern number, defined in the subregions of Brillouin zone, and construct a family of Chern dartboard insulators with quantized reduced Chern numbers but with trivial bulk topology. Chern dartboard insulators are protected by the mirror symmetries and exhibit distinct pseudospin textures, including (anti)skyrmions, inside the sub-Brillouin...

Realization of two-sublattice exchange physics in the triangular lattice compound Ba3Er(BO3)3

Ennis M
Bag R
Liu C
Dissanayake SE
Kolesnikov AI
Balents L
et al
2024

Geometric frustration commonly occurs in materials where magnetic rare-earth ions are arranged on a two-dimensional triangular lattice. These compounds have been gaining significant attention lately, as they hold the promise of revealing unique quantum states of matter. However, little attention has been devoted to cases where spin-12 rare-earth ions are substituted with ions exhibiting higher spin multiplicities. Here, we successfully synthesize high-quality single crystal samples of Ba3Er(BO3)3, which is part...