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arXiv · 1708.04126

Finite temperature Green's function approach for excited state and thermodynamic properties of cool to warm dense matter

J. J. Kas·J. J. Rehr
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Abstract

We present a finite-temperature extension of the retarded cumulant Green's function for calculations of exited-state and thermodynamic properties of electronic systems. The method incorporates a cumulant to leading order in the screened Coulomb interaction $W$ and improves excited state properties compared to the $GW$ approximation of many-body perturbation theory. Results for the homogeneous electron gas are presented for a wide range of densities and temperatures, from cool to warm dense matter regime, which reveal several hitherto unexpected properties. For example, correlation effects remain strong at high $T$ while the exchange-correlation energy becomes small. In addition, the spectral function broadens and damping increases with temperature, blurring the usual quasi-particle picture. Similarly Compton scattering exhibits substantial many-body corrections that persist at normal densities and intermediate $T$. Results for exchange-correlation energies and potentials are in good agreement with existing theories and finite-temperature DFT functionals.

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J. J. Kas, J. J. Rehr. 2017-07-25. Finite temperature Green's function approach for excited state and thermodynamic properties of cool to warm dense matter. https://doi.org/10.1103/physrevlett.119.176403

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