scholarly journals REEMERGENCE OF THE COLLECTIVE MODE IN 3HE AND ELECTRON LAYERS

2010 ◽  
Vol 24 (25n26) ◽  
pp. 4889-4900
Author(s):  
HELGA M. BÖHM ◽  
ROBERT HOLLER ◽  
ECKHARD KROTSCHECK ◽  
MARTIN PANHOLZER ◽  
HENRY GODFRIN ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Random Phase Approximation ◽  
Collective Mode ◽  
Random Phase ◽  
Landau Damping ◽  
Phase Approximation ◽  
Large Wave ◽  
Static Interaction ◽  
Low Energies ◽  
Unexpected Behavior

Neutron scattering experiments on a 3 He layer on graphite show an unexpected behavior of the collective mode. After having been broadened by Landau damping at intermediate wave vectors, the phonon-roton mode resharpens at large wave vectors and even emerges from the particle-hole continuum at low energies. The measured spectra cannot be explained by a random phase approximation with any static interaction. We show here that the data are well described if dynamic two-pair fluctuations are accounted for. We predict similar effects for electron layers.

scholarly journals Mermin dielectric function versus local field corrections on proton stopping in degenerate plasmas

2008 ◽  
Vol 26 (3) ◽  
pp. 389-395 ◽  
Author(s):  
M.D. Barriga-Carrasco
Keyword(s):  
Charged Particle ◽  
Local Field ◽  
Random Phase Approximation ◽  
Function Versus ◽  
Random Phase ◽  
Phase Approximation ◽  
Free Electrons ◽  
High Increase ◽  
Low Energies ◽  
Before And After

AbstractIf plasmas are considered fully ionized, the electronic stopping of a charged particle that traverses them will only be due to free electrons. This stopping can be obtained in a first view through the random phase approximation (RPA). But free electrons interact between them affecting the stopping. These interactions can be taken into account in the dielectric formalism by means of two different ways: the Mermin function or the local field corrections (LFCs). LFCs produce an enhancement in stopping before the maximum and recover the RPA values just after it. Mermin method also produces firstly a high increase at very low energies, then a small enhancement at low energies and finally decreases below RPA values before and after the maximum. Differences between the two methods are very important at very low energies and by 30% around the stopping maximum.

Interpretation of Preferential Adsorption Using Random Phase Approximation Theory

1995 ◽  
Vol 60 (10) ◽  
pp. 1641-1652 ◽  
Author(s):  
Henri C. Benoît ◽  
Claude Strazielle
Keyword(s):  
Approximation Theory ◽  
Random Phase Approximation ◽  
Virial Coefficient ◽  
Random Phase ◽  
Second Virial Coefficient ◽  
Solvent Mixture ◽  
Gyration Radius ◽  
Thermodynamic Quantities ◽  
Phase Approximation ◽  
Preferential Adsorption

It has been shown that in light scattering experiments with polymers replacement of a solvent by a solvent mixture causes problems due to preferential adsorption of one of the solvents. The present paper extends this theory to be applicable to any angle of observation and any concentration by using the random phase approximation theory proposed by de Gennes. The corresponding formulas provide expressions for molecular weight, gyration radius, and the second virial coefficient, which enables measurements of these quantities provided enough information on molecular and thermodynamic quantities is available.

Neutrino reactions onC12by the quasiparticle random-phase approximation (QRPA)

2010 ◽  
Vol 81 (2) ◽  
Author(s):  
Myung-Ki Cheoun ◽  
Eunja Ha ◽  
Su Youn Lee ◽  
K. S. Kim ◽  
W. Y. So ◽  
...  
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Phase Approximation ◽  
Quasiparticle Random Phase Approximation
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