Research

Theoretical condensed matter physics · first-principles simulation · high-performance computing for quantum materials.

Overview

I study how electrons, phonons, and light interact in real materials — and what those interactions can be tuned to do. My work combines density-functional and many-body perturbation theory with large-scale electron–phonon calculations (through the EPW code) to predict superconducting transition temperatures, transport coefficients, and optical responses from first principles, and I increasingly use machine learning to accelerate the search for promising materials.

Current projects

Superconductivity

I study conventional phonon-mediated superconductors on two fronts. In high-pressure hydrides such as H3S and D3S, the Migdal approximation — the textbook decoupling of electron and phonon propagators — is no longer safe: electrons and phonons share comparable energy scales. I compute electron–phonon vertex corrections, non-adiabatic effects, and anharmonic phonon contributions from first principles and measure their impact on the predicted Tc.

For conventional superconductors that remain well within the Migdal regime — such as Na-intercalated graphite — I combine stability searches with full Eliashberg-level electron–phonon calculations to chart a stability-superconductivity map that guides experimental synthesis.

Most recently, I tested these corrections side by side across seven hydrides, from H3S, YH6, and YH9 at megabar pressures to ambient-pressure PdH/D/T, and introduced two diagnostics, the anharmonic renormalization Aλ and the vertex ratio RV, that identify which approximation limits a given Tc prediction. The same corrections matter beyond hydrides: in the noncentrosymmetric superconductor NbReSi, anharmonicity and vertex corrections together bring Tc and the gap into agreement with experiment. With collaborators, I also study two-dimensional MXene and MBene superconductors, where phonon-mediated pairing coexists with nontrivial band topology.

Transport in topological semimetals

Weyl and Dirac semimetals host anomalous responses that descend from their Berry-curvature textures. We compute phonon-limited conductivity, mobility, and related transport coefficients for realistic materials at the Wannier-interpolated level, and we are developing data-driven models that extrapolate these properties across a family of candidates.

Crystal symmetry often decides where these signatures come from. In hexagonal TiAs, nonsymmorphic symmetry enforces fourfold band degeneracies and a strong topological index, and a Van Hove saddle point near the Fermi level shapes the anisotropic Fermi surface seen in angle-dependent magnetoresistance.

Light–matter interaction and ultrafast magnetism

Circularly polarized light can drive magnetization in metals through the inverse Faraday effect. We developed a gauge-invariant first-principles framework for this response and traced its systematic trends across the 3d, 4d, and 5d transition metals — setting the stage for practical ultrafast, all-optical magnetic control.

Energy materials and catalysis

Parallel to the quantum-materials program, we design two-dimensional anodes and cathodes for next-generation batteries (Si2BN, graphyne, graphdiyne) and model catalytic processes on oxide surfaces and heterointerfaces. The goal is an atomistic account of capacity, diffusion, and surface reactivity that experiment can act on.

Code development

EPW — Electron-Phonon Wannier

Core developer. Contributed the electron-phonon vertex correction implementation, a Berry curvature implementation for topological transport, and a two-level MPI parallelization that scales superconductivity calculations to dense k/q-grids.

WannierBerri

Contributed the inverse Faraday effect (IFE) implementation, enabling first-principles calculation of light-driven magnetization in metallic systems directly from Wannier-interpolated band structures.

EPWpy

Python workflow automation layer over EPW and Quantum ESPRESSO, built with collaborators at the Oden Institute, UT Austin. Abstracts many-body workflows (transport, superconductivity, optics) into reproducible scripts.

Collaborations

  • University of Maryland (Prof. Thomas E. Murphy, Prof. Pratibha Dev) — ultrafast optics and light-driven magnetism; defects in quantum materials.
  • SUNY Binghamton (Prof. E. R. Margine) — beyond-Migdal electron-phonon theory, transport in topological semimetals.
  • Tohoku University (Dr. Hitoshi Mori) — non-adiabatic and vertex-correction effects in hydride superconductors.
  • UC Riverside (Prof. Sinisa Coh, Prof. R. B. Wilson) — inverse Faraday effect and ultrafast optical experiments.
  • UT Austin (Prof. Feliciano Giustino) — EPW and EPWpy ecosystem, high-throughput many-body workflows.
  • IIT Madras (Prof. B. R. K. Nanda, Prof. Somnath Roy) — 2D materials, energy storage, catalysis, and oxide surface chemistry.
  • University of Michigan (Prof. Emmanouil Kioupakis) — first-principles transport in wide-bandgap and metastable phases.
  • Other collaborators — Prof. Ryosuke Akashi (Japan), Dr. Abinash Das, Dr. Y. Rambabu.