About

Vidvuds Ozolins is a Professor of Applied Physics & Materials Science at Yale University, with additional appointments in Applied & Computational Mathematics and Mechanical Engineering. His research interests are centered on first-principles computational modeling of high-performance materials, utilizing and developing theoretical methods for quantum mechanical calculations based on density functional theory (DFT) and beyond. His work incorporates modern statistical simulation methods such as Monte Carlo, molecular dynamics, and path integral molecular dynamics, with a focus on integrating recent advances in applied mathematics and machine learning to create rigorous, efficient, and highly automated high-throughput methods for materials design and discovery. His research topics include high-performance materials for energy storage and generation, thermodynamic and structural properties of solids at high temperatures, spin liquid materials for topological quantum computing, electron and phonon transport in bulk and nanostructured materials, thermoelectric phenomena, and mathematical approaches for solving partial differential equations in quantum mechanics and materials science. Ozolins has contributed to the development of novel computational techniques and has been involved in patenting methods related to thermoelectric materials. He holds a Ph.D. from the KTH Royal Institute of Technology and is recognized for his significant contributions to the field of materials science and applied physics.

Research topics

• Condensed matter physics
• Physics
• Optics
• Thermodynamics
• Materials science
• Quantum mechanics

Selected publications

• Improving neural network performance for solving quantum sign structure

  Physical review. B./Physical review. B · 2025-10-15 · 2 citations

  articleOpen accessSenior author

  Neural quantum states have emerged as a widely used approach to the numerical study of the ground states of nonstoquastic Hamiltonians. However, existing approaches often rely on a priori knowledge of the sign structure or require a separately pretrained phase network. We introduce a modified stochastic reconfiguration method that effectively uses differing imaginary time steps to evolve the amplitude and phase. Using a larger time step for phase optimization, this method enables a simultaneous and efficient training of phase and amplitude neural networks. The efficacy of our method is demonstrated on the Heisenberg ${J}_{1}\ensuremath{-}{J}_{2}$ model.

  PublisherOA PDFDOI

• A unified understanding of minimum lattice thermal conductivity

  Proceedings of the National Academy of Sciences · 2023-06-20 · 35 citations

  articleOpen access

  We propose a first-principles model of minimum lattice thermal conductivity ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msubsup> <mml:mi>κ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">min</mml:mi> </mml:msubsup> </mml:math> ) based on a unified theoretical treatment of thermal transport in crystals and glasses. We apply this model to thousands of inorganic compounds and find a universal behavior of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msubsup> <mml:mi>κ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">min</mml:mi> </mml:msubsup> </mml:math> in crystals in the high-temperature limit: The isotropically averaged <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msubsup> <mml:mi>κ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">min</mml:mi> </mml:msubsup> </mml:math> is independent of structural complexity and bounded within a range from ∼0.1 to ∼2.6 W/(m K), in striking contrast to the conventional phonon gas model which predicts no lower bound. We unveil the underlying physics by showing that for a given parent compound, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msubsup> <mml:mi>κ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">min</mml:mi> </mml:msubsup> </mml:math> is bounded from below by a value that is approximately insensitive to disorder, but the relative importance of different heat transport channels (phonon gas versus diffuson) depends strongly on the degree of disorder. Moreover, we propose that the diffuson-dominated <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msubsup> <mml:mi>κ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">min</mml:mi> </mml:msubsup> </mml:math> in complex and disordered compounds might be effectively approximated by the phonon gas model for an ordered compound by averaging out disorder and applying phonon unfolding. With these insights, we further bridge the knowledge gap between our model and the well-known Cahill–Watson–Pohl (CWP) model, rationalizing the successes and limitations of the CWP model in the absence of heat transfer mediated by diffusons. Finally, we construct graph network and random forest machine learning models to extend our predictions to all compounds within the Inorganic Crystal Structure Database (ICSD), which were validated against thermoelectric materials possessing experimentally measured ultralow κ L . Our work offers a unified understanding of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msubsup> <mml:mi>κ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">min</mml:mi> </mml:msubsup> </mml:math> , which can guide the rational engineering of materials to achieve <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:msubsup> <mml:mi>κ</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">L</mml:mi> </mml:mrow> <mml:mi mathvariant="normal">min</mml:mi> </mml:msubsup> </mml:math> .

  PublisherOA PDFDOI

• Optimal band structure for thermoelectrics with realistic scattering and bands

  npj Computational Materials · 2021-03-25 · 1 citations

  preprintOpen access

  Abstract Understanding how to optimize electronic band structures for thermoelectrics is a topic of long-standing interest in the community. Prior models have been limited to simplified bands and/or scattering models. In this study, we apply more rigorous scattering treatments to more realistic model band structures—upward-parabolic bands that inflect to an inverted-parabolic behavior—including cases of multiple bands. In contrast to common descriptors (e.g., quality factor and complexity factor), the degree to which multiple pockets improve thermoelectric performance is bounded by interband scattering and the relative shapes of the bands. We establish that extremely anisotropic “flat-and-dispersive” bands, although best-performing in theory, may not represent a promising design strategy in practice. Critically, we determine optimum bandwidth, dependent on temperature and lattice thermal conductivity, from perfect transport cutoffs that can in theory significantly boost z T beyond the values attainable through intrinsic band structures alone. Our analysis should be widely useful as the thermoelectric research community eyes z T &gt; 3.

  PublisherOA PDFDOI

• A variational framework for computing Wannier functions using dictionary learning

  Journal of Computational Physics · 2021-11-04

  articleSenior author
  PublisherDOI

• Coarsening of solid <i>β</i>-Sn particles in liquid Pb-Sn alloys: Reinterpretation of experimental data in the framework of trans-interface-diffusion-controlled coarsening

  Physical Review Materials · 2021-04-01 · 3 citations

  article

  Previously published data, not ours, on the coarsening of solid \ensuremath{\beta}-Sn particles in a liquid Pb-Sn matrix of near-eutectic composition are reanalyzed within the framework of the trans-interface-diffusion-controlled (TIDC) theory of coarsening. The data were obtained under conditions of microgravity from specimens heat-treated at 458 K and containing four equilibrium volume fractions ${f}_{e}$ equaling 0.10, 0.15, 0.20, and 0.30. We show that the rate constants $k({f}_{e})$ in the traditional coarsening equation ${\ensuremath{\langle}r\ensuremath{\rangle}}^{3}\ensuremath{\approx}k({f}_{e})t$ for the kinetics of growth of the average particle radius $\ensuremath{\langle}r\ensuremath{\rangle}$ are nearly independent of ${f}_{e}$, in disagreement with numerous theories wherein coarsening is controlled by diffusion in the host matrix phase. Atom transport in TIDC coarsening is instead controlled by slow diffusion through the diffuse interface, of width \ensuremath{\delta}, separating the dispersed particles from the matrix; the kinetics of this process is independent of ${f}_{e}$. Atomistic simulations were performed to estimate the properties of the solid-liquid (S-L) interface at 458 K, 2 K above the Pb-Sn eutectic temperature. The S-L interfaces normal to (001) and (010) of tetragonal \ensuremath{\beta}-Sn were examined and found to have nearly identical properties, including interface widths of \ensuremath{\sim}1.7 nm. In conjunction with the diffusivities in solid \ensuremath{\beta}-Sn and liquid hypereutectic Pb-Sn at 458 K, we estimate that TIDC coarsening should prevail for solid Sn particles \ensuremath{\sim}1700 \ensuremath{\mu}m in radius, far exceeding the maximum radius of \ensuremath{\sim}100 \ensuremath{\mu}m measured experimentally. The TIDC theory also predicts that the kinetics of growth obeys the equation ${\ensuremath{\langle}r\ensuremath{\rangle}}^{n}\ensuremath{\propto}t$. The temporal exponent $n$ was evaluated to be \ensuremath{\sim}2.5, as ascertained by analyzing data on the particle size distributions (PSDs; histograms) for the alloys with ${f}_{e}=0.15$, 0.20, and 0.30. The histograms were converted to experimental cumulative distribution functions (ECDFs) and analyzed using the Kolmogorov-Smirnov (K-S) test applied to the theoretical CDFs predicted by the TIDC theory. We report the first successful application of the K-S test to experimental PSDs concomitant with particle coarsening. From every aspect of the experimental data amenable to analysis, we conclude that the coarsening behavior of solid Sn particles in liquid hypereutectic Pb-Sn alloys is fully consistent with the predictions of the TIDC theory of coarsening.

  PublisherDOI

• High Thermoelectric Performance in Multi-pocketed Full-Heuslers and Their Defect Energetics

  arXiv (Cornell University) · 2020-03-11

  preprintOpen accessSenior author

  This study, utilizing high-fidelity methods for computing electron-phonon scattering rates, theoretically demonstrates that ultrahigh intrinsic bulk thermoelectric performance across cryogenic-to-high temperatures is physically possible. It also demonstrates the benefit of accidental band degeneracy to thermoelectric performance is conditional upon their characters. Full-Heusler Sr$_{2}$BiAu featuring ten energy-aligned dispersive pockets (six along $\Gamma-X$ and four at $L$) is herein predicted to be theoretically capable of delivering $zT=0.4-4.9$ at $100-700$ K. Relative to the previously investigated Ba$_{2}$BiAu, the additional $L$-pockets in Sr$_{2}$BiAu significantly increase the power factor at low temperatures, as high as 12 mW m$^{-1}$ K$^{-2}$ near room temperature. As temperature rises, the performance decays quickly and sinks below that of Ba$_{2}$BiAu due to the differing dispersion and scattering characteristics of the $L$ and $\Gamma-X$ states. Sr$_{2}$SbAu is generally projected to deliver worse performance due to the appreciable energy-misalignment in the two accessible band pockets. The dominant intrinsic defect at play is Bi/Sb$_{\text{Au}}$ antisites, which limit the $n$-dopabilities of all of the Heusler compounds. Calculations suggest only Sr$_{2}$SbAu potentially has both a large enough stability region and high enough Sb$_{\text{Au}}$ antisite formation energies to retain some small chance at experimental realization as a high-performing thermoelectric.

  Publisher

• High Thermoelectric Performance and Defect Energetics of Multipocketed Full Heusler Compounds

  Physical Review Applied · 2020-08-21 · 36 citations

  articleOpen accessSenior author

  Thermoelectrics are used in energy harvesting technology for power generation and refrigeration, but await breakthroughs with a higher figure of merit ($Z\phantom{\rule{0}{0ex}}T$), especially at room-to-cryogenic temperatures. Via explicit treatment of electron-phonon scattering, this study shows that multipocketed full Heusler compounds Sr${}_{2}$BiAu and Sr${}_{2}$SbAu could feature notably high theoretical $Z\phantom{\rule{0}{0ex}}T$. Stability and defects analysis also suggest that these compounds may be synthesizable and favorably $n$-type. A successful experimental realization of these compounds could pave new grounds in bulk thermoelectrics.

  PublisherOA PDFDOI

• Microscopic thermal transport mechanisms in Tl 3 VSe 4 : lattice phonons or localized oscillators?

  Bulletin of the American Physical Society · 2020-03-04

  article
  Publisher

• Particlelike Phonon Propagation Dominates Ultralow Lattice Thermal Conductivity in Crystalline <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>Tl</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mi>VSe</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

  Physical Review Letters · 2020 · 200 citations

  • Condensed matter physics
  • Physics
  • Quantum mechanics

  We investigate the microscopic mechanisms of ultralow lattice thermal conductivity (κ_{l}) in Tl_{3}VSe_{4} by combining a first principles density functional theory based framework of anharmonic lattice dynamics with the Peierls-Boltzmann transport equation for phonons. We include contributions of the three- and four-phonon scattering processes to the phonon lifetimes as well as the temperature dependent anharmonic renormalization of phonon energies arising from an unusually strong quartic anharmonicity in Tl_{3}VSe_{4}. In contrast to a recent report by Mukhopadhyay et al. [Science 360, 1455 (2018)SCIEAS0036-807510.1126/science.aar8072] which suggested that a significant contribution to κ_{l} arises from random walks among uncorrelated oscillators, we show that particlelike propagation of phonon excitations can successfully explain the experimentally observed ultralow κ_{l}. Our findings are further supported by explicit calculations of the off-diagonal terms of the heat current operator, which are found to be small and indicate that wavelike tunneling of heat carrying vibrations is of minor importance. Our results (i) resolve the discrepancy between the theoretical and experimental κ_{l}, (ii) offer new insights into the minimum κ_{l} achievable in Tl_{3}VSe_{4}, and (iii) highlight the importance of high order anharmonicity in low-κ_{l} systems. The methodology demonstrated here may be used to resolve the discrepancies between the experimentally measured and the theoretically calculated κ_{l} in skutterides and perovskites, as well as to understand the glasslike κ_{l} in complex crystals with strong anharmonicity, leading towards the goal of rational design of new materials.

  PublisherOA PDFDOI

• Optimal Band Structure for Thermoelectrics with Realistic Scattering and\n Bands

  arXiv (Cornell University) · 2020-10-17

  preprintOpen access

  Understanding how to optimize electronic band structures for thermoelectrics\nis a topic of long-standing interest in the community. Prior models have been\nlimited to simplified bands and/or scattering models. In this study, we apply\nmore rigorous scattering treatments to more realistic model band structures -\nupward-parabolic bands that inflect to an inverted parabolic behavior -\nincluding cases of multiple bands. In contrast to common descriptors (e.g.,\nquality factor and complexity factor), the degree to which multiple pockets\nimprove thermoelectric performance is bounded by interband scattering and the\nrelative shapes of the bands. We establish that extremely anisotropic\n`flat-and-dispersive' bands, although best-performing in theory, may not\nrepresent a promising design strategy in practice. Critically, we determine\noptimum bandwidth, dependent on temperature and lattice thermal conductivity,\nfrom perfect transport cutoffs that can in theory significantly boost $zT$\nbeyond the values attainable through intrinsic band structures alone. Our\nanalysis should be widely useful as the thermoelectric research community eyes\n$zT&gt;3$.\n

  PublisherOA PDFDOI

Recent grants

• ITR-(ASE)-(sim): Ab Initio Modeling of Self-Assembled Pattern Growth in Heteroepitaxial Alloy Films with Long-Range Elastic interactions

  NSF · $255k · 2004–2008

• First-principles design of strongly anharmonic crystalline solids with ultra-low lattice thermal conductivity

  NSF · $309k · 2017–2020

• Ab Initio Approaches to Martensitic Transformations in Metallic Alloys

  NSF · $300k · 2011–2015

• Collaborative Research: First-Principles Engineering of Nanoscale Kinetics in Advanced Hydrides

  NSF · $150k · 2007–2011

Frequent coauthors

• Chris Wolverton

  Northwestern University

  60 shared

• Fei Zhou

  Lawrence Livermore National Laboratory

  40 shared

• Eric H. Majzoub

  University of Missouri–St. Louis

  36 shared

• Yi Xia

  28 shared

• Mark Asta

  University of California, Berkeley

  26 shared

• Alex Zunger

  University of Colorado Boulder

  23 shared

• Feng‐Chuan Chuang

  17 shared

• Christopher Wolverton

  17 shared

Education

• Ph.D., Physics

  Yale University

  1990

• M.S., Physics

  Yale University

  1986

• B.S., Physics

  University of Latvia

  1983