The sc-COHSEX+GW and the static off-diagonal GW approaches to quasiparticle wavefunctions and energies

ORAL

Abstract

Within the conventional GW approach, density functional theory (DFT) is typically used as a mean-field starting point; the self-energy operator is evaluated to 1st order in the DFT Green's function G$_{0}$ and screened Coulomb interaction W$_{0}$. The quasiparticle energies are calculated from diagonal elements of $\Sigma$ in the DFT orbital basis. This approach works extraordinarily well for many materials but has limitations when the DFT states are far from the quasiparticle wavefunctions. In such cases, off-diagonal elements of $\Sigma$ in the mean-field basis are large and the full $\Sigma$ matrix is needed. The slow convergence of the off-diagonal elements make approaches requiring the explicit construction of this matrix prohibitively expensive. We present two alternative approaches based on the static (COHSEX) approximation that efficiently include the mean-field off-diagonal matrix element effects: a sc-COHSEX+GW approach where a renormalized basis is obtained from a self-consistent evaluation of quasiparticle wavefunctions in the static approximation and a less intensive treatment of just the off-diagonal elements within the COHSEX approximation. We show examples of the approaches for molecules and crystalline systems. Support by NSF DMR10-1006184, DOE DE-AC02-05CH11231.

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Authors

  • Jack Deslippe

    • University of California, Berkeley / Lawrence Berkeley National Lab
    • Phys Dept. UC Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Lab

  • Manish Jain

    • University of California, Berkeley and Lawrence Berkeley National Laboratory
    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California at Berkeley and Lawrence Berkeley National Laboratory

  • Georgy Samsonidze

    • University of California at Berkeley and Lawrence Berkeley National Lab

  • Marvin L. Cohen

    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • University of California, Berkeley
    • University of California Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Lab
    • Department of Physics, University of California, Berkeley, and Materials Science Division, Lawrence Berkeley National Laboratory

  • Steven G. Louie

    • University of California, Berkeley and Lawrence Berkeley National Laboratory
    • Department of Physics, University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley National Lab
    • UC Berkeley
    • Department of Physics, U. C. Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • University of California-Berkeley and Lawrence Berkeley National Lab
    • Department of Physics, University of California at Berkeley
    • Phys Dept. UC Berkeley
    • Department of Physics, University of California, Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
    • University of California at Berkeley and Lawrence Berkeley National Lab