About

Felipe Jornada is an Assistant Professor of Materials Science and Engineering at Stanford University. His research focuses on predicting and understanding excited-state phenomena in quantum and energy materials. He relies on high-performance computer calculations based on parameter-free, quantum-mechanical theories developed within his group to make reliable predictions on novel materials. His interests include studying fundamental aspects of excitations such as their lifetimes, dynamics, and stability or binding energies, and how these can be engineered in nanostructured and low-dimensional systems. His ultimate goal is to use atomistic calculations to rationally design new materials with applications in energy research, electronics, optoelectronics, and quantum technologies. Felipe received his Ph.D. in physics from UC Berkeley in 2017, where he focused on predicting the electronic and optical properties of quasi-two-dimensional materials like graphene and transition metal dichalcogenides. He completed his M.S. and B.A. in physics at the Federal University of Rio Grande do Sul, Brazil. He joined Stanford faculty in January 2020.

Research topics

• Physics
• Materials science
• Condensed matter physics
• Nanotechnology
• Quantum mechanics
• Computer Science
• Artificial Intelligence
• Chemical physics
• Chemistry
• Engineering
• Crystallography
• Management science
• Optics
• Nuclear physics
• Engineering physics
• Data science
• Nuclear magnetic resonance
• Mathematics

Selected publications

• Exciton thermalization dynamics in monolayer <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>MoS</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>: A first-principles Boltzmann equation study

  Physical review. B./Physical review. B · 2025-05-06 · 4 citations

  articleOpen access

  Understanding exciton thermalization is critical for optimizing optoelectronic and photocatalytic processes in many materials. However, it is hard to access the dynamics of such processes experimentally, especially on systems such as monolayer transition metal dichalcogenides, where various low-energy excitations pathways can compete for exciton thermalization. Here, we study exciton dynamics due to exciton-phonon scattering in monolayer ${\mathrm{MoS}}_{2}$ from a first-principles, interacting Green's function approach, to obtain the relaxation and thermalization of low-energy excitons following different initial excitations at different temperatures. We find that the thermalization occurs on a picosecond time scale at 300 K but can increase by an order of magnitude at 100 K. The long total thermalization time, owing to the nature of its excitonic band structure, is dominated by slow spin-flip scattering processes in monolayer ${\mathrm{MoS}}_{2}$. In contrast, thermalization of excitons in individual spin-aligned and spin-anti-aligned channels can be achieved within a few hundred fs when exciting higher-energy excitons. We further simulate the intensity spectrum of time-resolved angle-resolved photoemission spectroscopy experiments and anticipate that such calculations may serve as a map to correlate spectroscopic signatures with microscopic exciton dynamics.

  PublisherOA PDFDOI

• A comprehensive framework to simulate real-time chemical dynamics on a fault-tolerant quantum computer

  Research Square · 2025-09-18

  preprintOpen accessSenior author
  PublisherOA PDFDOI

• Ab initio mechanisms and design principles for photodesorption from TiO2

  npj Computational Materials · 2025-05-05

  articleOpen accessSenior author

  Photocatalytic reactions often exhibit fast kinetics and high product selectivity, qualities difficult to achieve simultaneously in thermal processes. However, photo-driven mechanisms remain poorly understood due to challenges in realistically modeling catalysts in optically excited states. Here, we apply many-body perturbation theory (MBPT) calculations to gain insight into these mechanisms by studying a prototypical photocatalytic reaction, proton desorption from a rutile TiO2 (110) surface. Our results reveal dramatic changes upon photoexcitation, including an over 50% reduction in the desorption energy and the emergence of an energy barrier. We rationalize these findings using a generalizable model based on Fano theory, and explain the surprising increase of excitonic effects as the proton detaches from the surface. Our model also connects the alignment of various ionization potentials to the shape of the excited-state potential energy surface. These results, not qualitatively captured by constrained density-functional theory, highlight how MBPT calculations can inform photocatalytic reaction design.

  PublisherOA PDFDOI

• A comprehensive framework to simulate real-time chemical dynamics on a fault-tolerant quantum computer

  ArXiv.org · 2025-04-08 · 1 citations

  preprintOpen access1st authorCorresponding

  We present a comprehensive end-to-end framework for simulating the real-time dynamics of chemical systems on a fault-tolerant quantum computer, incorporating both electronic and nuclear quantum degrees of freedom. An all-particle simulation is nominally efficient on a quantum computer, but practically infeasible. Hence, central to our approach is the construction of a first-quantized plane-wave algorithm making use of pseudoions. The latter consolidate chemically inactive electrons and the nucleus into a single effective dynamical ionic entity, extending the well-established concept of pseudopotentials in quantum chemistry to a two-body interaction. We explicitly describe efficient quantum circuits for initial state preparation across all degrees of freedom, as well as for block-encoding the Hamiltonian describing interacting pseudoions and chemically active electrons, by leveraging recent advances in quantum rejection sampling to optimize the implementations. To extract useful chemical information, we first design molecular fingerprints by combining density-functional calculations with machine learning techniques, and subsequently validate them through surrogate classical molecular dynamics simulations. These fingerprints are then coherently encoded on a quantum computer for efficient molecular identification via amplitude estimation. We provide an extensive analysis of the cost of running the algorithm on a fault-tolerant quantum computer for several chemically interesting systems. As an illustration, simulating the interaction between $\mathrm{NH_3}$ and $\mathrm{BF_3}$ (a 40-particle system) requires 808 logical qubits to encode the problem, and approximately $10^{11}$ Toffoli gates per femtosecond of time evolution. Our results establish a foundation for further quantum algorithm development targeting chemical and material dynamics.

  PublisherOA PDFDOI

• Surface conduction and reduced electrical resistivity in ultrathin noncrystalline NbP semimetal

  Science · 2025-01-02 · 26 citations

  articleOpen access

  The electrical resistivity of conventional metals such as copper is known to increase in thin films as a result of electron-surface scattering, thus limiting the performance of metals in nanoscale electronics. Here, we find an unusual reduction of resistivity with decreasing film thickness in niobium phosphide (NbP) semimetal deposited at relatively low temperatures of 400°C. In films thinner than 5 nanometers, the room temperature resistivity (~34 microhm centimeters for 1.5-nanometer-thick NbP) is up to six times lower than the resistivity of our bulk NbP films, and lower than conventional metals at similar thickness (typically about 100 microhm centimeters). The NbP films are not crystalline but display local nanocrystalline, short-range order within an amorphous matrix. Our analysis suggests that the lower effective resistivity is caused by conduction through surface channels, together with high surface carrier density and sufficiently good mobility as the film thickness is reduced. These results and the fundamental insights obtained here could enable ultrathin, low-resistivity wires for nanoelectronics beyond the limitations of conventional metals.

  PublisherOA PDFDOI

• Advancing Quantum Many-Body GW Calculations on Exascale Supercomputing Platforms

  2025-11-12 · 2 citations

  articleOpen access

  Advanced ab initio materials simulations face growing challenges as increasing systems and phenomena complexity requires higher accuracy, driving up computational demands. Quantum many-body GW methods are state-of-the-art for treating electronic excited states and couplings but often hindered due to the costly numerical complexity. Here, we present innovative implementations of advanced GW methods within the BerkeleyGW package, enabling large-scale simulations on Frontier and Aurora exascale platforms. Our approach demonstrates exceptional versatility for complex heterogeneous systems with up to 17,574 atoms, along with achieving true performance portability across GPU architectures. We demonstrate excellent strong and weak scaling to thousands of nodes, reaching double-precision core-kernel performance of 1.069 ExaFLOP/s on Frontier (9,408 nodes) and 707.52 PetaFLOP/s on Aurora (9,600 nodes), corresponding to 59.45% and 48.79% of peak, respectively. Our work demonstrates a breakthrough in utilizing exascale computing for quantum materials simulations, delivering unprecedented predictive capabilities for rational designs of future quantum technologies.

  PublisherDOI

• Terahertz field-induced giant symmetry modulations in a van der Waals antiferromagnet

  ArXiv.org · 2025-10-01

  preprintOpen access

  Strong-field terahertz (THz) excitations enable dynamic control over electronic, lattice and symmetry degrees of freedom in quantum materials. Here, we uncover pronounced terahertz-induced symmetry modulations and coherent phonon dynamics in the van der Waals antiferromagnet MnPS3, in which inversion symmetry is broken by its antiferromagnetic spin configuration. Time-resolved second harmonic generation measurements reveal long-lived giant oscillations in the antiferromagnetic phase, with amplitudes comparable to the equilibrium signal, driven by phonons involving percent-level atomic displacements relative to the equilibrium bond lengths. The temporal evolution of the rotational anisotropy patterns indicate a dynamic breaking of mirror symmetry, modulated by two vibrational modes at 1.7 THz and 4.5 THz, with the former corresponding to a hidden mode not observed in equilibrium spectroscopy. We show that these effects arise in part from a field-induced charge rearrangement mechanism that lowers the local crystal symmetry, and couples to the phonon modes. A long-lived field-driven response was uncovered with a complex THz polarization dependence which, in comparison to theory, indicates evidence for an antiferromagnetic-to-ferrimagnetic transition. Our results establish an effective field-tunable pathway for driving excitations otherwise weak in equilibrium, and for manipulating magnetism in low-dimensional materials via dynamical modulation of symmetry.

  PublisherOA PDFDOI

• Accurate, transferable, and verifiable machine-learned interatomic potentials for layered materials

  ArXiv.org · 2025-03-19 · 1 citations

  preprintOpen accessSenior author

  Twisted layered van-der-Waals materials often exhibit unique electronic and optical properties absent in their non-twisted counterparts. Unfortunately, predicting such properties is hindered by the difficulty in determining the atomic structure in materials displaying large moiré domains. Here, we introduce a split machine-learned interatomic potential and dataset curation approach that separates intralayer and interlayer interactions and significantly improves model accuracy -- with a tenfold increase in energy and force prediction accuracy relative to conventional models. We further demonstrate that traditional MLIP validation metrics -- force and energy errors -- are inadequate for moiré structures and develop a more holistic, physically-motivated metric based on the distribution of stacking configurations. This metric effectively compares the entirety of large-scale moiré domains between two structures instead of relying on conventional measures evaluated on smaller commensurate cells. Finally, we establish that one-dimensional instead of two-dimensional moiré structures can serve as efficient surrogate systems for validating MLIPs, allowing for a practical model validation protocol against explicit DFT calculations. Applying our framework to HfS2/GaS bilayers reveals that accurate structural predictions directly translate into reliable electronic properties. Our model-agnostic approach integrates seamlessly with various intralayer and interlayer interaction models, enabling computationally tractable relaxation of moiré materials, from bilayer to complex multilayers, with rigorously validated accuracy.

  PublisherOA PDFDOI

• Exciton-defect interaction and optical properties from a first-principles T-matrix approach

  ArXiv.org · 2025-05-21

  preprintOpen accessSenior author

  Understanding exciton-defect interactions is critical for optimizing optoelectronic and quantum information applications in many materials. However, ab initio simulations of material properties with defects are often limited to high defect density. Here, we study effects of exciton-defect interactions on optical absorption and photoluminescence spectra in monolayer MoS2 using a first-principles T-matrix approach. We demonstrate that exciton-defect bound states can be captured by the disorder-averaged Green's function with the T-matrix approximation and further analyze their optical properties. Our approach yields photoluminescence spectra in good agreement with experiments and provides a new, computationally efficient framework for simulating optical properties of disordered 2D materials from first-principles.

  PublisherOA PDFDOI

• Ab Initio Mechanisms and Design Principles for Photodesorption from TiO${}_2$

  ArXiv.org · 2025-03-05

  preprintOpen accessSenior author

  Photocatalytic reactions often exhibit fast kinetics and high product selectivity, qualities which are desirable but difficult to achieve simultaneously in thermally driven processes. However, photo-driven mechanisms are poorly understood owing to the difficulty in realistically modeling catalysts in optically excited states. Here we apply many-body perturbation theory (MBPT) calculations to gain insight into these mechanisms by studying a prototypical photocatalytic reaction, proton desorption from a rutile TiO${}_2$ (110) surface. Our calculations reveal a qualitatively different desorption process upon photoexcitation, with an over 50% reduction in the desorption energy and the emergence of an energy barrier. We rationalize these findings with a generalizable model based on Fano theory and explain the surprising increase of excitonic effects as the proton detaches from the surface. Our model also yields a connection between how the alignment of relevant ionization potentials affects the shape of the excited-state potential energy surface. These results cannot be qualitatively captured by typical constrained density-functional theory and highlight how contemporary first-principles MBPT calculations can be applied to design photocatalytic reactions.

  PublisherOA PDF

Recent grants

• DMREF: Collaborative research: Data driven discovery of synthesis pathways and distinguishing electronic phenomena of 1D van der Waals bonded solids

  NSF · $560k · 2019–2023

• CAREER: Electronic and Optical Properties in Generalized Moire Systems from First Principles

  NSF · $360k · 2023–2028

Frequent coauthors

• Steven G. Louie

  Lawrence Berkeley National Laboratory

  152 shared

• Diana Y. Qiu

  75 shared

• Jeffrey B. Neaton

  University of California, Berkeley

  65 shared

• Jack Deslippe

  Lawrence Berkeley National Laboratory

  51 shared

• Yang‐Hao Chan

  Institute of Atomic and Molecular Sciences, Academia Sinica

  47 shared

• Takashi Taniguchi

  25 shared

• Kenji Watanabe

  National Institute for Materials Science

  25 shared

• Mit H. Naik

  24 shared

Education

• Ph.D., Materials Science and Engineering

  Stanford University

  2015

• M.S., Materials Science and Engineering

  Stanford University

  2011

• B.S., Materials Science and Engineering

  University of California, Berkeley

  2009