3,852 research outputs found
Quarter-filled spin density wave states with long-range Coulomb interaction
Spin density wave (SDW) states at quarter-filling, which coexist with charge
density wave (CDW) states, have been examined where the critical temperature is
calculated for an extended Hubbard model with long range repulsive
interactions. Within the mean-field theory, it is shown that the first order
transition occurs with decreasing temperature for interactions located around
the boundary between SDW state and CDW state.Comment: 4 pages, 5 figures, Proceedings of CREST International Workshop
(Nagoya, Japan, 24-26 January, 2000), submitted to J. Phys. Chem. Solid
Solution of Two-Body Bound State Problems with Confining Potentials
The homogeneous Lippmann-Schwinger integral equation is solved in momentum
space by using confining potentials. Since the confining potentials are
unbounded at large distances, they lead to a singularity at small momentum. In
order to remove the singularity of the kernel of the integral equation, a
regularized form of the potentials is used. As an application of the method,
the mass spectra of heavy quarkonia, mesons consisting from heavy quark and
antiquark , are calculated for linear and
quadratic confining potentials. The results are in good agreement with
configuration space and experimental results.Comment: 6 pages, 5 table
Schnol's theorem and spectral properties of massless Dirac operators with scalar potentials
The spectra of massless Dirac operators are of essential interest e.g. for
the electronic properties of graphene, but fundamental questions such as the
existence of spectral gaps remain open. We show that the eigenvalues of
massless Dirac operators with suitable real-valued potentials lie inside small
sets easily characterised in terms of properties of the potentials, and we
prove a Schnol'-type theorem relating spectral points to polynomial boundedness
of solutions of the Dirac equation. Moreover, we show that, under minimal
hypotheses which leave the potential essentially unrestrained in large parts of
space, the spectrum of the massless Dirac operator covers the whole real line;
in particular, this will be the case if the potential is nearly constant in a
sequence of regions.Comment: 18 page
Toward the Application of Three-Dimensional Approach to Few-body Atomic Bound States
The first step toward the application of an effective non partial wave (PW)
numerical approach to few-body atomic bound states has been taken. The two-body
transition amplitude which appears in the kernel of three-dimensional
Faddeev-Yakubovsky integral equations is calculated as function of two-body
Jacobi momentum vectors, i.e. as a function of the magnitude of initial and
final momentum vectors and the angle between them. For numerical calculation
the realistic interatomic interactions HFDHE2, HFD-B, LM2M2 and TTY are used.
The angular and momentum dependence of the fully off-shell transition amplitude
is studied at negative energies. It has been numerically shown that, similar to
the nuclear case, the transition amplitude exhibits a characteristic angular
behavior in the vicinity of 4He dimer pole.Comment: 8 pages, 6 figures, 4 tables. Oral contribution to the 19th
International IUPAP Conference on Few-Body Problems In Physics, 31 Aug-5 Sep
2009, Bonn, German
Relativistic three-particle dynamical equations: II. Application to the trinucleon system
We calculate the contribution of relativistic dynamics on the
neutron-deuteron scattering length and triton binding energy employing five
sets trinucleon potential models and four types of three-dimensional
relativistic three-body equations suggested in the preceding paper. The
relativistic correction to binding energy may vary a lot and even change sign
depending on the relativistic formulation employed. The deviations of these
observables from those obtained in nonrelativistic models follow the general
universal trend of deviations introduced by off- and on-shell variations of
two- and three-nucleon potentials in a nonrelativistic model calculation.
Consequently, it will be difficult to separate unambiguously the effect of off-
and on-shell variations of two- and three- nucleon potentials on low-energy
three-nucleon observables from the effect of relativistic dynamics.Comment: 15 pages, [Text and one postscript figure included, e-mail:
[email protected]; Fax: 55-11-288 8224] Report # IFT P.069/9
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Nonequilibrium transport on a quantum molecular chain in terms of the complex Liouvillian spectrum
The transport process in a molecular chain in a nonequilibrium stationary state is theoretically investigated. The molecule is interacting at both ends with thermal baths of different temperatures, while no dissipation mechanism is contained inside the molecular chain. We have first obtained the nonequilibrium stationary state outside the Hilbert space in terms of the complex spectral representation of Liouvillian. The nonequilibrium stationary state is obtained as an eigenstate of the Liouvillian, which is constructed through the collision invariant of the kinetic equation. The eigenstate of the Liouvillian contains information on the spatial correlation between the molecular chain and the thermal baths. While energy flow in the nonequilibrium state which is due to the first-order correlation can be described by the Landauer formula, the particle current due to the second-order correlation cannot be described by the Landauer formula. The present method provides a simple way to evaluate the energy transport in a molecular chain in a nonequilibrium situation.Ministry of Education, Science, Sports, and Culture of JapanYukawa International Program for Quark-Hadron Sciences YIPQSPhysic
Charged three-body system with arbitrary masses near conformal invariance
Within an adiabatic approximation to the three-body Coulomb system, we study
the strength of the leading order conformaly invariant attractive dipole
interaction produced when a slow charged particle (with mass ) is
captured by the first excited state of a dimer [with individual masses and
charges ) and ()]. The approach leads to a universal
mass-charge critical condition for the existence of three-body level
condensation, , as well as the ratio between the geometrically scaled energy levels.
The resulting expressions can be relevant in the analysis of recent
experimental setups with charged three-body systems, such as the interactions
of excitons, or other matter-antimatter dimers, with a slow charged particle.Comment: 5 pages, 1 figure, to appear in Physical Review
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