2,551 research outputs found
Degenerate approach to the mean field Bose- Hubbard Hamiltonian
A degenerate variant of mean field perturbation theory for the on-site
Bose-Hubbard Hamiltonian is presented. We split the perturbation into two terms
and perform exact diagonalization in the two-dimensional subspace corresponding
to the degenerate states. The final relations for the second order ground state
energy and first order wave function do not contain singularities at integer
values of the chemical potentials. The resulting equation for the phase
boundary between superfluid and Mott states coincides with the prediction based
on the conventional mean field perturbation approach.Comment: 4 pages, 1 figur
Vortex state in Bose-Fermi mixture with attraction between bosons and fermions
Vortex states in the mixture of ultracold atomic clouds of bosons and
fermions are investigated using the effective Hamiltonian for the Bose
subsystem. A stability of the Bose system in the case of attractive interaction
between components is studied in the framework of variational Bose wave
function and Thomas-Fermi approximation. It is shown that the critical number
of bosons increases in the presence of the vortex.Comment: 7 pages, 8 figure
Quasi-binary amorphous phase in a 3D system of particles with repulsive-shoulder interactions
We report a computer-simulation study of the equilibrium phase diagram of a
three-dimensional system of particles with a repulsive step potential. Using
free-energy calculations, we have determined the equilibrium phase diagram of
this system. At low temperatures, we observe a number of distinct crystal
phases. However, under certain conditions the system undergoes a glass
transition in a regime where the liquid appears thermodynamically stable. We
argue that the appearance of this amorphous low-temperature phase can be
understood by viewing this one-component system as a pseudo-binary mixture.Comment: 4 pages, 4 figure
Structure of a Solvated Nickel(II) Complex of (\u3cem\u3eS\u3c/em\u3e)-2\u27-(\u3cem\u3eN\u3c/em\u3e-benzylprolyl)aminoacetophenone and (\u3cem\u3eR\u3c/em\u3e)-valine Schiff base, C\u3csub\u3e25\u3c/sub\u3eH\u3csub\u3e29\u3c/sub\u3eN\u3csub\u3e3\u3c/sub\u3eNiO\u3csub\u3e3\u3c/sub\u3e.1/2C\u3csub\u3e4\u3c/sub\u3eH\u3csub\u3e8\u3c/sub\u3eO. Conformational Calculation of Diastereomeric Complexes of (\u3cem\u3eR\u3c/em\u3e)-valine and (\u3cem\u3eS\u3c/em\u3e)-valine
Giant oscillations of energy levels in mesoscopic superconductors
The interplay of geometrical and Andreev quantization in mesoscopic
superconductors leads to giant mesoscopic oscillations of energy levels as
functions of the Fermi momentum and/or sample size. Quantization rules are
formulated for closed quasiparticle trajectories in the presence of normal
scattering at the sample boundaries. Two generic examples of mesoscopic systems
are studied: (i) one dimensional Andreev states in a quantum box, (ii) a single
vortex in a mesoscopic cylinder.Comment: 4 pages, 3 figure
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