1,548 research outputs found
Schwinger boson mean field theory of the Heisenberg Ferrimagnetic Spin Chain
The Schwinger boson mean field theory is applied to the quantum ferrimagnetic
Heisenberg chain. There is a ferrimagnetic long range order in the ground
state. We observe two branches of the low lying excitation and calculate the
spin reduction, the gap of the antiferromagnetic branch, and the spin
fluctuation at . These results agree with the established numerical
results quite well. At finite temperatures, the long range order is destroyed
because of the disappearance of the Bose condensation. The thermodynamic
observables, such as the free energy, magnetic susceptibility, specific heat,
and the spin correlation at , are calculated. The has a
minimum at intermediate temperatures and the spin correlation length behaves as
at low temperatures. These qualitatively agree with the numerical
results and the difference is small at low temperatures.Comment: 15 pages, 5 figures. Accepted by Phys. Rev.
Electronic and Structural Properties of C Molecule
The extended SSH model and Bogoliubov-de Gennes(BdeG) formalism are applied
to investigate the electronic properties and stable lattice configurations of
C. We focus the problem on the molecule's unusual symmetry. The
electronic part of the Hamiltonian without Coulomb interaction is solved
analytically. We find that the gap between HOMO and LUMO is small due to the
long distance hopping between the 2nd and 5th layers. The charge densities of
HOMO and LUMO are mainly distributed in the two layers, that causes a large
splitting between the spin triplet and singlet excitons. The differences of
bond lengths, angles and charge densities among the molecule and polarons are
discussed.Comment: 15 pages, 4 figures, 4 Table
Correlation effects for semiconducting single wall carbon nanotube: a density matrix renormalization group study
In this paper, we report the applicability of the density matrix
renormalization group(DMRG) approach to the cylindrical single wall carbon
nanotube (SWCN) for purpose of its correlation effect. By applying the DMRG
approach to the ++ model, with and being the hopping and
Coulomb energies between the nearest neighboring sites, respectively, and
the onsite Coulomb energy, we calculate the phase diagram for the SWCN with
chiral numbers (), which reflects the competition between the
correlation energy and . Within reasonable parameter ranges, we
investigate possible correlated groundstates, the lowest excitations and the
corresponding correlation functions in which the connection with the excitonic
insulator is particularly addressed.Comment: 1 source files, 5 figure
The order analysis for the two loop corrections to lepton MDM
The experimental data of the magnetic dipole moment(MDM) of lepton(,
) is very exact. The deviation between the experimental data and the
standard model prediction maybe come from new physics contribution.
In the supersymmetric models, there are very many two loop diagrams
contributing to the lepton MDM. In supersymmetric models, we suppose two mass
scales and with for supersymmetric particles.
Squarks belong to and the other supersymmetric particles belong to
. We analyze the order of the contributions from the two loop diagrams. The
two loop triangle diagrams corresponding to the two loop self-energy diagram
satisfy Ward-identity, and their contributions possess particular factors. This
work can help to distinguish the important two loop diagrams giving corrections
to lepton MDM.Comment: 12 pages, 3 figure
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