We develop a method to calculate the polarizability of a many-electron system within Green's function theory in a similar way as within time-dependent density functional theory and apply it to Si and GaAs. The method joins the computational simplicity of the latter with the accuracy of the former approach. The resulting exchange-correlation many-body kernel ${f}_{\mathrm{xc}}^{\mathrm{FQP}}$ and optical spectra are in good agreement with those obtained by the solution of the Bethe-Salpeter equation.We develop a method to calculate the polarizability of a many-electron system within Green's function theory in a similar way as within time-dependent density functional theory and apply it to Si and GaAs. The method joins the computational simplicity of the latter with the accuracy of the former approach. The resulting exchange-correlation many-body kernel ${f}_{\mathrm{xc}}^{\mathrm{FQP}}$ and optical spectra are in good agreement with those obtained by the solution of the Bethe-Salpeter equation.

Physical review. B, Condensed matterOct 29, 200388 citations

Time-Dependent Density Functional Theory

Chaoyuan Zhu

Nov 30, 202211 citations

Helium Atom Excitations by the GW and Bethe-Salpeter Many-Body Formalism

Jing Li, Markus Holzmann, Ivan Duchemin +2 more

The helium atom is the simplest many-body electronic system provided by nature. The exact solution to the Schrödinger equation is known for helium ground and excited states, and it represents a benchmark for any many-body methodology. Here, we check the ab initio many-body GW approximation and the Bethe-Salpeter equation (BSE) against the exact solution for helium. Starting from the Hartree-Fock method, we show that the GW and the BSE yield impressively accurate results on excitation energies and oscillator strength, systematically improving the time-dependent Hartree-Fock method. These findings suggest that the accuracy of the BSE and GW approximations is not significantly limited by self-interaction and self-screening problems even in this few electron limit. We further discuss our results in comparison to those obtained by time-dependent density-functional theory.The helium atom is the simplest many-body electronic system provided by nature. The exact solution to the Schrödinger equation is known for helium ground and excited states, and it represents a benchmark for any many-body methodology. Here, we check the ab initio many-body GW approximation and the Bethe-Salpeter equation (BSE) against the exact solution for helium. Starting from the Hartree-Fock method, we show that the GW and the BSE yield impressively accurate results on excitation energies and oscillator strength, systematically improving the time-dependent Hartree-Fock method. These findings suggest that the accuracy of the BSE and GW approximations is not significantly limited by self-interaction and self-screening problems even in this few electron limit. We further discuss our results in comparison to those obtained by time-dependent density-functional theory.

arXiv:1611.07456Physical Review LettersApr 17, 201729 citations

{f}_{\mathrm{xc}}^{\mathrm{FQP}}

and optical spectra are in good agreement with those obtained by the solution of the Bethe-Salpeter equation.