Spectral Density Calculations for Solids with Selected Configuration Interaction

ORAL

Abstract

In this presentation, we will discuss spectral density analysis of molecules and solids through many-body theory, using multireference wavefunctions in the framework of selected configuration interaction (sCI). This method allows controlled convergence to the full CI limit within a given basis set at a fraction of the cost by iteratively updating a reference wavefunction with a small set of determinants with large contributions to the wavefunction energy. sCI can calculate properties of ground-state and excited-state wavefunctions with similar levels of accuracy, making it a unique ab initio method. We implemented a Green's function approach to calculating spectral densities, for which we will discuss relevant computational pragmatic strategies and convergence behaviors. We successfully predict core and valence excitations for several molecules and will discuss spectral density results for the strongly correlated hydrogen chain and periodic silicon.

*L. Rangel DaCosta was supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research, Department of Energy Computational Science Graduate Fellowship under Award Number DE-SC0021110. A. Benali and K. Gasperich were funded by U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as part of the Computational Materials Sciences Program and Center for Predictive Simulation of Functional Materials. DFT and DMC calculations used an award of computer time provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research has used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC0206CH1135. M Caffarel was supported by the ANR PhemSpec project, grant ANR-18-CE30-0025-02 of the French Agence Nationale de la Recherche.

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Presenters

  • Luis Rangel DaCosta

    • University of California, Berkeley

Authors

  • Luis Rangel DaCosta

    • University of California, Berkeley

  • kevin gasperich

    • Argonne National Laboratory

  • Michel Caffarel

    • Laboratoire de Chimie et Physique Quantiques (UMR 5626), Universite de Toulouse, CNRS

  • Anouar Benali

    • Argonne National Laboratory