Localization in fluids: A comparison of competing theories and their application to positron annihilation

Journal Article · Wed Aug 15 00:00:00 EDT 1990 · Physical Review, A (General Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevA.42.2228· OSTI ID:6506520

Miller, B N; Fan, Y ^[1]

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1. Department of Physics, Texas Christian University, Fort Worth, TX (USA)

This paper addresses two central issues in our understanding of self-trapping, or localization, of a light particle (e.g., electron, positron, or positronium atom) in a fluid. The first concerns the relationship between the mean-field calculations of localized states carried out from the mid-1950s until the present, and the direct calculation of light-particle (LP) properties from the adiabatic model. The second concerns the universality of the ring polymer representation of the LP, which has proved to be extremely useful for computing the properties of localized electrons. We first demonstrate that the mean-field theories of localization, which are derived from density functionals, can be obtained from the adiabatic model by employing a Gutzwiller type of approximation. We then study the application of the adiabatic model, via the polymer representation, to the annihilation of positrons and positronium atoms in a fluid. Expressions for the decay rate and its variance are derived in terms of the two- and three-point distribution functions for the polymer sites and positions of the atomic nuclei. The momentum distribution of the localized LP is shown to be proportional to the Fourier transform of the distribution function for the displacement between the ends of a broken polymer.

• OSTI ID: 6506520
• Journal Information: Physical Review, A (General Physics); (USA), Vol. 42:4; ISSN 0556-2791
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
FLUIDS
TRAPPED ELECTRONS
POSITRONIUM
ANNIHILATION
POSITRONS
TRAPPING
DISTRIBUTION FUNCTIONS
MEAN-FIELD THEORY
ANTILEPTONS
ANTIMATTER
ANTIPARTICLES
BASIC INTERACTIONS
ELECTROMAGNETIC INTERACTIONS
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
FUNCTIONS
INTERACTIONS
LEPTONS
640303* - Atomic
Molecular & Chemical Physics- Positronium
Muonium
& Muonic & Mesic Atoms & Molecules