scholarly journals Optical Response of an Interacting Polaron Gas in Strongly Polar Crystals

2020 ◽  
Vol 10 (6) ◽  
pp. 2059
Author(s):  
Serghei Klimin ◽  
Jacques Tempere ◽  
Jozef T. Devreese ◽  
Cesare Franchini ◽  
Georg Kresse
Keyword(s):  
Optical Conductivity ◽  
Random Phase Approximation ◽  
Random Phase ◽  
Optical Response ◽  
Longitudinal Optical ◽  
Electron Interaction ◽  
Present Calculation ◽  
Polar Crystals ◽  
Dynamic Screening ◽  
Conductivity Spectra

Optical conductivity of an interacting polaron gas is calculated within an extended random phase approximation which takes into account mixing of collective excitations of the electron gas with longitudinal optical (LO) phonons. This mixing is important for the optical response of strongly polar crystals where the static dielectric constant is rather high, as in the case of strontium titanate. The present calculation sheds light on unexplained features of experimentally observed optical conductivity spectra in n-doped SrTiO 3 . These features appear to be due to dynamic screening of the electron–electron interaction by polar optical phonons and hence do not require additional mechanisms for their explanation.

QUASIPARTICLE LIFETIME OF A TWO-DIMENSIONAL ELECTRON GAS

2010 ◽  
Vol 24 (09) ◽  
pp. 1103-1110
Author(s):  
A. ESMAILIAN ◽  
M. R. ABOLHASSANI
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Electron Gas ◽  
Electron Interaction ◽  
Two Dimensional ◽  
Effective Electron ◽  
2D Electron Gas ◽  
Small Correction ◽  
Electron Relaxation ◽  
Dimensional Electron Gas

We calculate the inelastic scattering lifetime of an excited quasiparticle at low (or zero) temperature, due to electron-electron interaction for a clean two-dimensional (2D) electron gas within the random-phase approximation (RPA) and compare it with the lifetime measured from the tunnelling experiment. Our result obtained by direct numerical calculation increases the electron relaxation rate considerably, hence decreases the size of discrepancy (roughly by a factor of 4) between theory and experiment which exists in the literature. We also show that including local-field factors in the effective electron interaction yields small correction to the result calculated within the RPA for rs ~ 1, corresponding to electron density of the sample in the tunnelling experiment. This result suggests that the RPA is reasonably accurate for a 2D electron gas in weak coupling limit.

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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