578 research outputs found
Comment on: rotational properties of trapped bosons
Based on the Hellman-Feynman theorem it is shown that the average square
radius of a cloud of interacting bosons in a parabolic well can be derived from
their free energy. As an application, the temperature dependence of the moment
of inertia of non-interacting bosons in a parabolic trap is determined as a
function of the number of bosons. Well below the critical condensation
temperature, the Bose-Einstein statistics are found to substantially reduce the
moment of inertia of this system, as compared to a gas of ``distinguishable''
particles in a parabolic well.Comment: Herewith we repost our paper cond-mat/9611090 (1996). It was
published in Phys. Rev. A 55, 2453 (March 1997), three years before
cond-mat/0003471 (2000) by Schneider and Wallis. Reposted by
[email protected]
The center-of-mass response of confined systems
For confined systems of identical particles, either bosons or fermions, we
argue that the parabolic nature of the confinement potential is a prerequisite
for the non-dissipative character of the center of mass response to a uniform
probe. For an excitation in a parabolic confining potential, the half width of
the density response function depends nevertheless quantitatively on properties
of the internal degrees of freedom, as is illustrated here for an ideal
confined gas of identical particles with harmonic interparticle interactions.Comment: 4 pages REVTEX; accepted as Brief Communication in Phys. Rev.
Variational path-integral treatment of a translation invariant many-polaron system
A translation invariant N-polaron system is investigated at arbitrary
electron-phonon coupling strength, using a variational principle for path
integrals for identical particles. An upper bound for the ground state energy
is found as a function of the number of spin up and spin down polarons, taking
the electron-electron interaction and the Fermi statistics into account. The
resulting addition energies and the criteria for multipolaron formation are
discussed.Comment: 22 pages, 5 figures, 1 table, E-mail addresses:
[email protected], [email protected], [email protected]
Switching Boundary Conditions in the Many-Body Diffusion Algorithm
In this paper we show how the transposition, the basic operation of the
permutation group, can be taken into account in a diffusion process of
identical particles. Whereas in an earlier approach the method was applied to
systems in which the potential is invariant under interchanging the Cartesian
components of the particle coordinates, this condition on the potential is
avoided here. In general, the potential introduces a switching of the boundary
conditions of the walkers. These transitions modelled by a continuous-time
Markov chain generate sample paths for the propagator as a Feynman-Kac
functional. A few examples, including harmonic fermions with an anharmonic
interaction, and the ground-state energy of ortho-helium are studied to
elucidate the theoretical discussion and to illustrate the feasibility of a
sign-problem-free implementation scheme for the recently developed many-body
diffusion approach.Comment: 16 pages REVTEX + 6 postscript figures, submitted to Phys. Rev. E on
Jan. 27, 199
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