Energy and structure of dilute hard- and soft-sphere gases

Journal Article · Sun Jun 01 04:00:00 EDT 2003 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.67.063615· OSTI ID:20639808

Mazzanti, F ^[1]; Polls, A ^[2]; Fabrocini, A ^[3]

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1. Departament d'Electronica, Enginyeria i Arquitectura La Salle, Pg. Bonanova 8, Universitat Ramon Llull, E-08022 Barcelona (Spain)
2. Departament d'Estructura i Constituents de la Materia, Diagonal 645, Universitat de Barcelona, E-08028 Barcelona (Spain)
3. Dipartimento di Fisica 'E. Fermi', Universita di Pisa, and INFN, Sezione di Pisa, Via Buonarroti, 2, I-56100 Pisa (Italy)

The energy and structure of dilute hard- and soft-sphere Bose gases are systematically studied in the framework of several many-body approaches, such as the variational correlated theory, the Bogoliubov model, and the uniform limit approximation, valid in the weak-interaction regime. When possible, the results are compared with the exact diffusion Monte Carlo ones. Jastrow-type correlation provides a good description of the systems, both hard- and soft-spheres, if the hypernetted chain energy functional is freely minimized and the resulting Euler equation is solved. The study of the soft-sphere potentials confirms the appearance of a dependence of the energy on the shape of the potential at gas paremeter values of x{approx}0.001. For quantities other than the energy, such as the radial distribution functions and the momentum distributions, the dependence appears at any value of x. The occurrence of a maximum in the radial distribution function, in the momentum distribution, and in the excitation spectrum is a natural effect of the correlations when x increases. The asymptotic behaviors of the functions characterizing the structure of the systems are also investigated. The uniform limit approach is very easy to implement and provides a good description of the soft-sphere gas. Its reliability improves when the interaction weakens.

• OSTI ID: 20639808
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 6 Vol. 67; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
BOSE-EINSTEIN GAS
BOSONS
CORRELATIONS
DIFFUSION
EXCITATION
MANY-BODY PROBLEM
MONTE CARLO METHOD
POTENTIALS
SPATIAL DISTRIBUTION
SPHERES
VARIATIONAL METHODS
WEAK INTERACTIONS