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1. Incorporating the effect of spin–orbit interaction in Auger decay spectra: Theory and examples

   https://doi.org/10.1063/5.0272198  

   Jayadev, Nayanthara K; Skomorowski, Wojciech; Krylov, Anna I (September 2025, The Journal of Chemical Physics)

   A theoretical framework for computing Auger spectra that include spin-orbit interaction is presented. The framework is based on the state-interaction approach using equation-of-motion coupled-cluster wave-functions. The working equations for Auger decay rates are derived within the Feshbach–Fano formalism. The capabilities of the theory are illustrated by the calculation of L-edge Auger spectra of H2S and Ar using the Feshbach–Fano and complex basis function (CBF) approaches. The quality of the Feshbach–Fano results depends critically on the treatment of the free-electron state. In contrast to the K-edge spectra for which both plane wave and Coulomb wave treatments yield reasonable results, the Feshbach–Fano calculations yield accurate results for L-edges only when using Coulomb wave (FF-CW). The FF-CW and CBF calculations of Auger spectra in H2S and Ar agree well with each other and with the available experimental data. The results highlight the importance of spin–orbit interactions for modeling L-edge Auger spectra. 

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2. Explicitly correlated Gaussian basis approach to periodic systems

   https://doi.org/10.1063/5.0343454  

   Varga, Kálmán (July 2026, The Journal of Chemical Physics)

   Closed-form expressions for all matrix elements required for variational calculation of the electronic structure of periodic solids have been derived using a basis of explicitly correlated Gaussians. Periodic basis functions are constructed by summing shifted correlated Gaussians over all composite lattice translations, where a generalized unfolding theorem reduces the resulting double lattice sum to a single sum through a unified computational framework for overlap, kinetic energy, and Coulomb potential operators. The formalism has been validated through application to an infinite one-dimensional hydrogen chain, where the ground-state energy per atom computed in the thermodynamic limit is shown to agree with finite-chain results extrapolated by many other many-body methods. 

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3. Relativistic two-component double ionization potential equation-of-motion coupled cluster with the Dirac–Coulomb–Breit Hamiltonian

   https://doi.org/10.1063/5.0278675  

   Li, Run R; Yuwono, Stephen H; Liebenthal, Marcus D; Zhang, Tianyuan; Li, Xiaosong; DePrince, A Eugene (September 2025, The Journal of Chemical Physics)

   We present an implementation of relativistic double ionization potential (DIP) equation-of-motion coupled cluster (EOMCC) with up to 4-hole–2-particle (4h2p) excitations that makes use of the molecular mean-field exact two-component (mmfX2C) framework. We apply mmfX2C-DIP-EOMCC to several neutral atoms and diatomic molecules to obtain the ground and first few excited states of the corresponding dication species, and we observe excellent agreement (to within 0.001 eV) between DIPs obtained from mmfX2C- and four-component DIP-EOMCC calculations that include 3-hole–1-particle (3h1p) excitations, with either the Dirac–Coulomb or Dirac–Coulomb–Gaunt Hamiltonians. We also compare double IPs for mmfX2C-DIP-EOMCC calculations with the full Dirac–Coulomb–Breit Hamiltonian to those from experiment. The mmfX2C-DIP-EOMCC with 3h1p excitations leads to errors in absolute double IPs that generally overestimate experimental data for noble gases by 0.1–0.4 eV, whereas the inclusion of 4h2p excitations results in double IPs that are too low by 0.1–0.2 eV, at the large basis set limit. 

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4. Self-consistent Coulomb interactions from constrained dynamical mean-field theory

   https://doi.org/10.1103/yb1w-8cxm  

   Sihi, Antik; Mandal, Subhasish; Haule, Kristjan (May 2026, Physical Review B)

   We develop a self-consistent first-principles framework for determining the screened Coulomb interaction strength (U) based on constrained dynamical mean-field theory (cDMFT). Unlike conventional approaches, this method incorporates essential vertex corrections within the same embedded-DMFT formalism used for the electronic structure calculation. Using the cDMFT-derived interaction strengths as input to embedded DMFT yields spectral functions in excellent agreement with photoemission experiments across a wide range of materials, spanning 3d to 5d transition-metal compounds, including correlated metals, Mott insulators, altermagnets, and unconventional superconductors. This unified many-body framework establishes a systematic first-principles route for determining interaction strengths in correlated materials and substantially enhances the predictive power of DFT + DMFT and its extensions. 

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5. Phonon screening and dissociation of excitons at finite temperatures from first principles

   https://doi.org/10.1073/pnas.2403434121  

   Alvertis, Antonios M; Haber, Jonah B; Li, Zhenglu; Coveney, Christopher_J N; Louie, Steven G; Filip, Marina R; Neaton, Jeffrey B (July 2024, Proceedings of the National Academy of Sciences)

   The properties of excitons, or correlated electron–hole pairs, are of paramount importance to optoelectronic applications of materials. A central component of exciton physics is the electron–hole interaction, which is commonly treated as screened solely by electrons within a material. However, nuclear motion can screen this Coulomb interaction as well, with several recent studies developing model approaches for approximating the phonon screening of excitonic properties. While these model approaches tend to improve agreement with experiment, they rely on several approximations that restrict their applicability to a wide range of materials, and thus far they have neglected the effect of finite temperatures. Here, we develop a fully first-principles, parameter-free approach to compute the temperature-dependent effects of phonon screening within the ab initio $\mathit{GW}$ -Bethe–Salpeter equation framework. We recover previously proposed models of phonon screening as well-defined limits of our general framework, and discuss their validity by comparing them against our first-principles results. We develop an efficient computational workflow and apply it to a diverse set of semiconductors, specifically AlN, CdS, GaN, MgO, and ${\text{SrTiO}}_3$ . We demonstrate under different physical scenarios how excitons may be screened by multiple polar optical or acoustic phonons, how their binding energies can exhibit strong temperature dependence, and the ultrafast timescales on which they dissociate into free electron–hole pairs. 

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