Perturbo is a software package for first-principles calculations of charge transport and ultrafast carrier dynamics in materials. The current version focuses on electron-phonon interactions and can compute phonon-limited transport properties such as the conductivity, carrier mobility and Seebeck coefficient. It can also simulate the ultrafast nonequilibrium electron dynamics in the presence of electron-phonon scattering. Perturbo uses results from density functional theory and density functional perturbation theory calculations as input, and employs Wannier interpolation to reduce the computational cost. It supports norm-conserving and ultrasoft pseudopotentials, spin-orbit coupling, and polar electron-phonon corrections for bulk and 2D materials. Hybrid MPI plus OpenMP parallelization is implemented to enable efficient calculations on large systems (up to at least 50 atoms) using high-performance computing. Taken together, Perturbo provides efficient and broadly applicable ab initio tools to investigate electron-phonon interactions and carrier dynamics quantitatively in metals, semiconductors, insulators, and 2D materials.

Next-generation batteries based on divalent working ions have the potential to both reduce the cost of energy storage devices and increase performance. Examples of promising divalent systems include those based on Mg 2+ , Ca 2+ , and Zn 2+ working ions. Development of such technologies is slow, however, in part due to the difficulty associated with divalent cation conduction in the solid state. Divalent ion conduction is especially challenging in insulating materials that would be useful as solid-state electrolytes or protecting layers on the surfaces of metal anodes. Furthermore, there are no reports of divalent cation conduction in insulating, inorganic materials at reasonable temperatures, prohibiting the development of structure− property relationships. Here, we report Zn 2+ conduction in insulating ZnPS 3 , demonstrating divalent ionic conductivity in an ordered, inorganic lattice near room temperature. Importantly, the activation energy associated with the bulk conductivity is low, 351 ± 99 meV, comparable to some Li + conductors such as LTTO, although not as low as the superionic Li + conductors. First-principles calculations suggest that the barrier corresponds to vacancy-mediated diffusion. Assessment of the structural distortions observed along the ion diffusion pathways suggests that an increase in the P−P−S bond angle in the [P 2 S 6 ] 4− moiety accommodates the Zn 2+ as it passes through the high-energy intermediate coordination environments. ZnPS 3 now represents a baseline material family to begin developing the structure−property relationships that control divalent ion diffusion and conduction in insulating solid-state hosts.

Electron-defect (e-d) interactions govern charge carrier dynamics at low temperature, where they limit the carrier mobility and give rise to phenomena of broad relevance in condensed matter physics. Ab initio calculations of e-d interactions are still in their infancy, mainly because they require large supercells and computationally expensive workflows. Here we develop an efficient ab initio approach for computing elastic e-d interactions, their associated e-d relaxation times (RTs), and the lowtemperature defect-limited carrier mobility. The method is applied to silicon with simple neutral defects, such as vacancies and interstitials. Contrary to conventional wisdom, the computed e-d RTs depend strongly on carrier energy and defect type, and the defect-limited mobility is temperature dependent. These results highlight the shortcomings of widely employed heuristic models of e-d interactions in materials. Our method opens new avenues for studying e-d scattering and lowtemperature charge transport from first principles.

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Computing electron-defect (e-d) interactions from first principles has remained impractical due to computational cost. Here we develop an interpolation scheme based on maximally localized Wannier functions (WFs) to efficiently compute e-d interaction matrix elements. The interpolated matrix elements can accurately reproduce those computed directly without interpolation, and the approach can significantly speed up calculations of e-d relaxation times and defect-limited charge transport. We show example calculations of vacancy defects in silicon and copper, for which we compute the e-d relaxation times on fine uniform and random Brillouin zone grids (and for copper, directly on the Fermi surface) as well as the defect-limited resistivity at low temperature. Our interpolation approach opens doors for atomistic calculations of charge carrier dynamics in the presence of defects.