Surface excitations in the random phase approximation

1970 ◽  
Vol 48 (21) ◽  
pp. 2592-2605 ◽  
Author(s):  
John Harris ◽  
Allan Griffin
Keyword(s):  
Random Phase Approximation ◽  
Short Range ◽  
Function Method ◽  
Wigner Distribution ◽  
Random Phase ◽  
Density Fluctuations ◽  
Wigner Distribution Function ◽  
Surface Modes ◽  
Inhomogeneous Systems ◽  
Two Component

Density fluctuations in inhomogeneous systems are treated in the RPA using the Kadanoff–Baym Green's function method. In our analysis, the Wigner distribution function plays an important role. Well-known results for surface plasmons in one- and two-component plasmas are very easy to derive. A brief discussion is given of surface modes in systems for which the interaction is of short range.

scholarly journals DENSITY-DEPENDENT PHONORITON STATES IN HIGHLY EXCITED SEMICONDUCTORS

1995 ◽  
Vol 09 (28) ◽  
pp. 3725-3733
Author(s):  
NGUYEN HONG QUANG ◽  
NGUYEN MINH KHUE
Keyword(s):  
Green's Function ◽  
Random Phase Approximation ◽  
Function Method ◽  
Random Phase ◽  
High Density ◽  
Phase Approximation ◽  
Green’S Function Method ◽  
Exciton Density ◽  
Density Dependent ◽  
Exciton Interaction

The dynamical aspects of the phonoriton state in highly-photoexcited semiconductors is studied theoretically. The effect of the exciton–exciton interaction and nonbosonic character of high-density excitons are taken into account. Using Green's function method and within the Random Phase Approximation it is shown that the phonoriton dispersion and damping are very sensitive to the exciton density, characterizing the excitation degree of semiconductors.

scholarly journals γ-ray strength function for astrophysical applications in the IAEA-CRP

2020 ◽  
Vol 239 ◽  
pp. 07005
Author(s):  
Hiroaki Utsunomiya ◽  
Stephane Goriely ◽  
Therese Renstrøm ◽  
Gry M. Tveten ◽  
Takashi Ari-izumi ◽  
...  
Keyword(s):  
Cross Sections ◽  
Random Phase Approximation ◽  
Function Method ◽  
Strength Function ◽  
Random Phase ◽  
Phase Approximation ◽  
Quasiparticle Random Phase Approximation ◽  
Hartree Fock ◽  
Γ Ray

The γ-ray strength function (γSF) is a nuclear quantity that governs photoabsorption in (γ, n) and photoemission in (n, γ) reactions. Within the framework of the γ-ray strength function method, we use (γ, n) cross sections as experimental constraints on the γSF from the Hartree-Fock-Bogolyubov plus quasiparticle-random phase approximation based on the Gogny D1M interaction for E1 and M1 components. The experimentally constrained γSF is further supplemented with the zero-limit M1 and E1 strengths to construct the downward γSF with which (n, γ) cross sections are calculated. We investigate (n, γ) cross sections in the context of astrophysical applications over the nickel and barium isotopic chains along the s-process path.

MAGNETOPLASMA OSCILLATIONS OF A TWO-DIMENSIONAL, TWO-COMPONENT PLASMA

1996 ◽  
Vol 10 (16) ◽  
pp. 737-744
Author(s):  
NGUYEN QUOC KHANH
Keyword(s):  
Random Phase Approximation ◽  
Random Phase ◽  
Three Dimensional ◽  
Collective Modes ◽  
Two Dimensional ◽  
Long Wavelength ◽  
Effective Masses ◽  
Two Component ◽  
Component Plasma ◽  
The Individual

We investigate the magnetoplasma excitations in a system comprised of two parallel two-dimensional conducting layers separated by a distance 2d>0. The individual layers are assumed to have, in general, different effective masses, particle densities and charges. The dispersion equations are derived quantum mechanically within the random phase approximation and the spectrum of the long wavelength collective modes is calculated. We also investigate the mutual phase of two-dimensional magnetoplasma oscillations and show that this mutual phase is similar to that in the three-dimensional case and does not depend on the interlayer distance.

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