Linear response functions of an interacting Fermi gas at T = 0

Thesis/Dissertation · Fri Jan 01 04:00:00 EST 1993

OSTI ID:7160706

Nimalakirthi, R

The response of an interacting Fermi gas in its ground state to weak external electromagnetic fields is analyzed in this thesis. The system's response to arbitrary scalar and vector potentials has been studied within the random phase approximation. The electrical response is characterized via the nonlocal polarizability density denoted by a(r,r[prime]; [omega]), which gives the polarization P(r, [omega]) induced at point r in a system by a perturbing electric field E(r[prime], [omega]) acting at the point r[prime], within linear response. A homogeneous electron gas at zero temperature is selected as a well characterized system, for the purpose of determining the nonlocal polarizability density and thus gaining information about the nature and functional form of a(r,r[prime], [omega]). The longitudinal component (in k space) of the nonlocal polarizability density a(r,r; [omega]) is connected to the dielectric function [epsilon](k, [omega]), and this connection is used to obtain results at two levels of approximation. Results from the Thomas-Fermi (TF) form and the random phase approximation (RPA) for [epsilon](k, [omega]) are compared. At TF level, the nonlocal polarizability density is evaluated analytically, while within the RPA asymptotic analytical results are obtained. The RPA results are qualitatively distinct from the TF results. The results indicate the possibility of long-range intramolecular terms in the nonlocal polarizability densities of individual molecules. For molecular systems, the change in nonlocal polariability density due to an infinitesimal shift in nuclear position is determined by the hyperpolarizability density. A method is provided to obtain the asymptotic form of the dynamic charge density susceptibility, as a function of space and time variables, for a homogeneous electron gas treated within the RPA.

• Research Organization: Michigan State Univ., East Lansing, MI (United States)
• OSTI ID: 7160706
• Country of Publication: United States
• Language: English

Related Subjects

664000* -- Atomic & Molecular Physics-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ATOMIC MODELS
CURRENT DENSITY
ELECTRICAL PROPERTIES
ELECTRO-OPTICAL EFFECTS
ELECTROMAGNETIC FIELDS
FERMI GAS
FLUIDS
GASES
MATHEMATICAL MODELS
PHYSICAL PROPERTIES
POLARIZABILITY
RANDOM PHASE APPROXIMATION
TEMPERATURE ZERO K
THOMAS-FERMI MODEL