All Publications

  • Giant Plasmon-Exciton Coupling in Small Plasmonic Nanoparticles from an Ab Initio GW-BSE Approach. Nano letters Simmerman, E. M., Altman, A. R., da Jornada, F. H. 2026

    Abstract

    Plasmonic nanocatalysts have emerged as highly tunable photocatalytic systems for driving nonequilibrium chemistry. However, the underlying microscopic mechanisms are poorly understood, since prevailing models wash out many-body interactions or atomistic details. Here, we address this gap by studying a prototypical small plasmonic nanoparticle within a first-principles GW plus Bethe-Salpeter equation approach. Despite their metallic composition, we find that electronic correlations qualitatively change the electronic and optical properties of this system. The optical response is dominated by plexcitons─plasmons hybridized with strongly bound (>2 eV) electron-hole pairs─showing that the established understanding of nanoparticles underpinned by free electron models is qualitatively incorrect for small nanoparticles. Additionally, we develop a quantitative metric of plasmonicity based on the excited-state wavefunctions and find that one dopant atom perturbs both the low-energy excitons and plasmonic states. Our results suggest that excitonic effects may influence optically driven chemical reactions in small metallic nanoparticles.

    View details for DOI 10.1021/acs.nanolett.5c05340

    View details for PubMedID 41587340

  • Ab initio mechanisms and design principles for photodesorption from TiO<sub>2</sub> NPJ COMPUTATIONAL MATERIALS Altman, A. R., da Jornada, F. H. 2025; 11 (1)

    View details for DOI 10.1038/s41524-025-01612-7

    View details for Web of Science ID 001482765700003

  • Mixed Stochastic-Deterministic Approach for Many-Body Perturbation Theory Calculations. Physical review letters Altman, A. R., Kundu, S., da Jornada, F. H. 2024; 132 (8): 086401

    Abstract

    We present an approach for GW calculations of quasiparticle energies with quasiquadratic scaling by approximating high-energy contributions to the Green's function in its Lehmann representation with effective stochastic vectors. The method is easy to implement without altering the GW code, converges rapidly with stochastic parameters, and treats systems of various dimensionality and screening response. Our calculations on a 5.75° twisted MoS_{2} bilayer show how large-scale GW methods include geometry relaxations and electronic correlations on an equal basis in structurally nontrivial materials.

    View details for DOI 10.1103/PhysRevLett.132.086401

    View details for PubMedID 38457735

  • Identifying Hidden Intracell Symmetries in Molecular Crystals and Their Impact for Multiexciton Generation. The journal of physical chemistry letters Altman, A. R., Refaely-Abramson, S., da Jornada, F. H. 1800: 747-753

    Abstract

    Organic molecular crystals are appealing for next-generation optoelectronic applications due to their multiexciton generation processes that can increase the efficiency of photovoltaic devices. However, a general understanding of how crystal structures affect these processes is lacking, requiring computationally demanding calculations for each material. Here we present an approach to understand and classify organic crystals and elucidate multiexciton processes. We show that organic crystals that are composed of two sublattices are well-approximated by effective fictitious systems of higher translational symmetry. Within this framework, we derive hidden selection rules in crystal pentacene and predict that the bulk polymorph supports fast Coulomb-mediated singlet fission with a transition rate about 2 orders of magnitude faster than that of the thin-film polymorph, a result confirmed with many-body perturbation theory calculations. Our approach is based on density-functional theory calculations and provides design principles for the experimental and computational discovery of new materials with tailored excitonic properties.

    View details for DOI 10.1021/acs.jpclett.1c03540

    View details for PubMedID 35029407

  • Charge-spin interconversion in epitaxial Pt probed by spin-orbit torques in a magnetic insulator PHYSICAL REVIEW MATERIALS Li, P., Riddiford, L. J., Bi, C., Wisser, J. J., Sun, X., Vailionis, A., Veit, M. J., Altman, A., Li, X., Mahendra, D. C., Wang, S. X., Suzuki, Y., Emori, S. 2021; 5 (6)

    View details for DOI 10.1103/PhysRevMaterials.5.064404

    View details for Web of Science ID 000661932200002

  • The role of iron in magnetic damping of Mg(Al,Fe)(2)O-4 spinel ferrite thin films APPLIED PHYSICS LETTERS Wisser, J. J., Riddiford, L. J., Altman, A., Li, P., Emori, S., Shafer, P., Klewe, C., NDiaye, A. T., Arenholz, E., Suzuki, Y. 2020; 116 (14)

    View details for DOI 10.1063/5.0003628

    View details for Web of Science ID 000526869500001

  • Ultrathin interfacial layer with suppressed room temperature magnetization in magnesium aluminum ferrite thin films APPLIED PHYSICS LETTERS Wisser, J. J., Emori, S., Riddiford, L., Altman, A., Li, P., Mahalingam, K., Urwin, B. T., Howe, B. M., Page, M. R., Grutter, A. J., Kirby, B. J., Suzuki, Y. 2019; 115 (13)

    View details for DOI 10.1063/1.5111326

    View details for Web of Science ID 000487997400005