Do hydrodynamic models misestimate exchange effects? Comparison with kinetic theory for electrostatic waves
arXiv:1809.05423 · doi:10.1063/1.5104339
Abstract
We have extended previous kinetic results to compute the exchange correction to the electrostatic electron susceptibility for arbitrary frequencies and wavenumbers in the low temperature limit. This has allowed us to make a general comparison with a much used hydrodynamic expression for exchange effects. It is found that the hydrodynamic expression gives a useful approximation when the phase velocity is roughly a factor larger than the Fermi velocity. For low phase velocities, as for ion-acoustic waves, wave-particle interaction leads to a strong enhancement of the exchange correction and the hydrodynamic results is smaller by an order of magnitude.
arXiv comment6 pages, 2 figures; submitted to Physics of Plasmas
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