English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We study the dynamical equation of the time-ordered Green's function atfinite temperature. We show that the time-ordered Green's function obeys aconventional Dyson equation only at equilibrium and in the limit ofzero-temperature. In all other cases, i.e. finite-temperature at equilibrium ornon-equilibrium, the time-ordered Green's function obeys instead a modifiedDyson equation. The derivation of this result is obtained from the generalformalism of the non-equilibrium Green's functions on the Keldysh time-loopcontour. At equilibrium, our result is fully consistent with the Matsubaratemperature Green's function formalism and also justifies rigorously thecorrection terms introduced in an ad hoc way with Hedin and Lundqvist. Ourresults show that one should use the appropriate dynamical equation for thetime-ordered Green's function when working beyond the equilibriumzero-temperature limit.

Dynamical equations for time-ordered Green's functions: from the Keldysh time-loop contour to equilibrium at finite and zero temperature