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Green's Function Perspective on the Nonlinear Density Response of Quantum Many-Body Systems
Jan Vorberger1, Tobias Dornheim1,2, Maximilian P Böhme3
1Helmholtz-Zentrum Dresden-Rossendorf (HZDR), 01328 Dresden, Germany.
Abstract:
We derive equations of motion for higher order density response functions using the theory of thermodynamic Green's functions. We also derive expressions for the higher order generalized dielectric functions and polarization functions. Moreover, we relate higher order response functions and higher order collision integrals within the Martin-Schwinger hierarchy. We expect our results to be highly relevant to the study of a variety of quantum many-body systems such as matter under extreme temperatures, densities, and pressures.
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where R is the gas constant (8.314 J/K·mol), T is the absolute temperature in kelvin, and Q is the reaction quotient. This equation may be used to predict the spontaneity of a process under any given set of conditions.
Reaction Quotient...

