共查询到20条相似文献,搜索用时 31 毫秒
1.
J. -B. Fournier 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,11(2):261-272
A phenomenological Landau elasticity for the shape, dilation, and lipid-tilt of bilayer membranes is developed. The shape
mode couples with the sum of the monolayers' tilt, while the dilation mode couples with the difference of the monolayers'
tilts. Interactions among membrane inclusions within regular arrays are discussed. Inclusions modifying the membrane thickness
and/or inducing a tilt-difference due to their convex or concave shape yield a dilation-induced attraction and a tilt-difference-induced
repulsion. The resulting interaction can stabilize 2D crystal phases, with the possible coexistence of different lattice spacings when the dilation-tilt-difference coupling is
large. Inclusions favoring crystals are those with either a long-convex or a short-concave hydrophobic core. Inclusions inducing
a local membrane curvature due to their conical shape repel one another. At short inclusions separations, a tilt comparable
with the inclusion's cone angle develops: it relaxes the membrane curvature and reduces the repulsion. At large separations
the tilt vanishes, whatever the value of the shape-tilt coupling.
Received 23 October 1998 and Received in final form 12 January 1999 相似文献
2.
M. Konôpka V. Bužek 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(2):285-293
We propose a method for entangling a system of two-level atoms in photonic crystals. The atoms are assumed to move in void
regions of a photonic crystal. The interaction between the atoms is mediated either via a defect mode or via a resonant dipole-dipole interaction. We show that these interactions can produce pure entangled atomic states. We analyze the problem with parameters typical
for currently existing photonic crystals and Rydberg atoms and we show that the atoms can emerge from photonic crystals in
entangled states. Depending on the linear dimensions of the crystal we estimate that a pair of atoms entangled in a photonic
crystal can be separated by tens of centimeters.
Receive 11 June 1999 and Received in final form 4 October 1999 相似文献
3.
R. Holzlöhner M. Schoen 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(3):413-419
The fluctuation-induced interaction between two rod-like, rigid inclusions in a fluid vesicle is studied by means of canonical
ensemble Monte-Carlo simulations. The vesicle membrane is represented by a triangulated network of hard spheres. Five rigidly
connected hard spheres form rod-like inclusions that can leap between sites of the triangular network. Their effective interaction
potential is computed as a function of mutual distance and angle of the inclusions. On account of the hard-core potential
among these, the nature of the potential is purely entropic. Special precaution is taken to reduce lattice artifacts and the
influence of finite-size effects due to the spherical geometry. Our results show that the effective potential is attractive
and short-range compared with the rod length L. Its well depth is of the order of , where is the bending modulus.
Received 5 February 1999 and Received in final form 14 May 1999 相似文献
4.
Yuan Chen Shuohong Guo Zhibing Li Aijun Ye 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(1):97-104
The kinetic spherical model with long-ranged interactions and an arbitrary initial order m0 quenched from a very high temperature to T
is solved. In the short-time regime, the bulk order increases with a power law in both the critical and phase-ordering dynamics.
To the latter dynamics, a power law for the relative order is found in the intermediate time-regime. The short-time scaling relations of small m0 are generalized to an arbitrary m0 and all the time larger than . The characteristic functions for the scaling of m0 and for are obtained. The crossover between scaling regimes is discussed in detail.
Received 17 September 1999 相似文献
5.
We have performed small angle neutron scattering experiments on the binary fluid mixture n-C6H14+n-C8F18 imbibed inside porous Vycor glass in the thermodynamic region corresponding to the bulk critical one. The resulting structure
can be represented as the sum of a temperature dependent Lorentzian term and a term describing the interference between the
porous matrix, a shell part richer in one component coating the glass surface, and a core part richer in the other component.
We observe critical fluctuations extending over distances markedly larger than the mean pore size.
Received 20 May 1999 相似文献
6.
M. Oba K. Akaoka M. Miyabe I. Wakaida 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(3):349-352
We measured Zeeman effect of atomic uranium spectra using laser induced fluorescence spectroscopy, and derived the J-value and g-factor of the second step levels. J-values and g-factors of high lying odd levels could be obtained. These data, especially the g-factors, have almost been unknown so far. We could verify our method which can be useful to measure J-values and g-factors of high lying levels of complex atoms like uranium.
Received 27 July 1999 and Received in final form 30 November 1999 相似文献
7.
D. Loison K.D. Schotte 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(1):125-137
Starting from the hypothesis of a second order transition we have studied modifications of the original Heisenberg antiferromagnet
on a stacked triangular lattice (STA-model) by the Monte Carlo technique. The change is a local constraint restricting the
spins at the corners of selected triangles to add up to zero without stopping them from moving freely (STAR-model). We have
studied also the closely related dihedral and trihedral models which can be classified as Stiefel models. We have found indications
of a first order transition for all three modified models instead of a universal critical behavior. This is in accordance
with the renormalization group investigations but disagrees with the Monte Carlo simulations of the original STA-model favoring
a new universality class. For the corresponding x-y antiferromagnet studied before, the second order nature of the transition could also not be confirmed.
Received 17 May 1999 and Received in final form 30 July 1999 相似文献
8.
The effect of rigid inclusions on the phase behavior of a film containing a mixture of lipid molecules is investigated. In
the proposed model, the inclusion-induced deformation of the film, and the resulting energy cost are strongly dependent upon
the spontaneous curvature of the mixed film. The spontaneous curvature is in turn strongly influenced by the composition of
film. This coupling between the film composition and the energy per inclusion leads to a lateral modulation of the composition,
which follows the local curvature of the membrane. In particular, it is shown that inclusions may induce a global phase separation
in a film which would otherwise be homogeneously mixed. The mixed film is then composed of patches of different average composition,
separated by the inclusions. This process may be of relevance to explain some aspects of lipid-protein association in biological
membranes.
Received 8 April 1999 and Received in final form 4 October 1999 相似文献
9.
J.M. de Araújo F.A. da Costa F.D. Nobre 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(4):661-667
A spin-1 model, appropriated to study the competition between bilinear (J
ij
S
i
S
j
) and biquadratic (K
ij
S
i
2
S
j
2) random interactions, both of them with zero mean, is investigated. The interactions are infinite-ranged and the replica
method is employed. Within the replica-symmetric assumption, the system presents two phases, namely, paramagnetic and spin-glass,
separated by a continuous transition line. The stability analysis of the replica-symmetric solution yields, besides the usual
instability associated with the spin-glass ordering, a new phase due to the random biquadratic couplings between the spins.
Received 18 May 1999 and Received in final form 20 October 1999 相似文献
10.
D.A. Garanin K. Kladko P. Fulde 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(2):293-300
We extend and apply a previously developed method for a semiclassical treatment of a system with large spin S. A multisite Heisenberg Hamiltonian is transformed into an effective classical Hamilton function which can be treated by
standard methods for classical systems. Quantum effects enter in form of multispin interactions in the Hamilton function. The latter is written in the form of an expansion in powers of J/(TS), where J is the coupling constant. Main ingredients of our method are spin coherent states and cumulants. Rules and diagrams are derived
for computing cumulants of groups of operators entering the Hamiltonian. The theory is illustrated by calculating the quantum
corrections to the free energy of a Heisenberg chain which were previously computed by a Wigner-Kirkwood expansion.
Received 5 May 1999 and received in final form 24 September 1999 相似文献
11.
The freezing transition of a network model for tensionless membranes confined to two dimensions is investigated by Monte Carlo
simulations and scaling arguments. In this model, a freezing transition is induced by reducing the tether length. Translational
and bond-orientational order parameters and elastic constants are determined as a function of the tether length. A finite-size
scaling analysis is used to show that the crystal melts via successive dislocation and disclination unbinding transitions, in qualitative agreement with the predictions of the Kosterlitz-Thouless-Halperin-Nelson-Young
theory. The hexatic phase is found to be stable over only a very small interval of tether lengths.
Received 4 June 1999 and Revised in final form 1 September 1999 相似文献
12.
K.J. Wiese 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,1(3):273-276
The dynamical scaling properties of selfavoiding polymerized membranes with internal dimension D embedded into d dimensions are studied including hydrodynamical interactions. It is shown that the theory is renormalizable to all orders
in perturbation theory and that the dynamical scaling exponent z is given by z=d. The crossover to the region, where the membrane is crumpled swollen but the hydrodynamic interaction irrelevant is discussed.
The results apply as well to polymers (D=1) as to membranes (D=2).
Received: 5 September 1997 / Accepted: 17 November 1997 相似文献
13.
In the asymptotic limit, the interlayer exchange coupling decays as D-2, where D is the spacer thickness. A systematic procedure for calculating the preasymptotic corrections, i.e., the terms of order D-n with ,is presented. The temperature dependence of the preasymptotic corrections is calculated. The results are used to discuss
the preasymptotic corrections for the Co/Cu/Co(001) system.
Received 7 January 1999 相似文献
14.
U. Pustogowa C. Blaas C. Uiberacker J. Zabloudil P. Weinberger L. Szunyogh C. Sommers 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,16(4):653-658
The magnetic properties of (ConPdm)r superstructures on Pd(100) and Pd(111) are evaluated using the fully-relativistic spin-polarized screened Korringa-Kohn-Rostoker
method. It is found that only in the case of a Pd(111) substrate such superstructures exhibit perpendicular magnetism, while
on a Pd(100) substrate the magnetization is oriented in-plane. Also investigated is the effect of interdiffusion in repeated
superstructures. By using the inhomogeneous coherent potential approximation (CPA) for layered systems the effect of ordering
into (repeated) superstructures can be described in an ab-initio-like manner. It is found that already small amounts of interdiffusion can be decisive for the actual value of the magnetic
anisotropy energy.
Received 3 November 1999 and Received in final form 18 January 2000 相似文献
15.
Zu Wei Yan Xi Xia Liang 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(3):531-538
A variational theory is proposed to study the surface states of electrons in a semi-infinite ternary mixed crystal, by taking
the effect of electron-surface optical (SO) phonon interaction into account. The energy and the wave function of the electronic
surface-states are calculated. The numerical results of the energies of the surface states of the polarons and the self-trapping
energies are obtained as functions of the composition x and surface potential V0 for several ternary mixed crystal materials. The results show that the electron-phonon interaction lowers the surface-state
levels with the energies from several to scores of meV. It is also found that the self-trapping energy of the surface polaron
has a minimum at some middle value of the composition x. It is indicated that the electron-phonon coupling effect can not be neglected.
Received 4 January 1999 and Received in final form 7 January 2000 相似文献
16.
H. Chamati D.M. Danchev N.S. Tonchev 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(2):307-316
A d-dimensional quantum model system confined to a general hypercubical geometry with linear spatial size L and “temporal size” 1/T ( T - temperature of the system) is considered in the spherical approximation under periodic boundary conditions. For a film
geometry in different space dimensions , where is a parameter controlling the decay of the long-range interaction, the free energy and the Casimir amplitudes are given.
We have proven that, if , the Casimir amplitude of the model, characterizing the leading temperature corrections to its ground state, is . The last implies that the universal constant of the model remains the same for both short, as well as long-range interactions, if one takes the normalization factor for
the Gaussian model to be such that . This is a generalization to the case of long-range interaction of the well-known result due to Sachdev. That constant differs
from the corresponding one characterizing the leading finite-size corrections at zero temperature which for is .
Received 3 June 1999 and Received in final form 16 August 1999 相似文献
17.
N. Petit F. Gervais P. Buvat P. Hourquebie P. Topart 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,12(3):367-372
The reflectivity spectrum of a polyaniline CSA-doped in presence of m-cresol has been measured over the wide wavenumber range
of 15- 9 000 cm
-1 (0.002-1.1 eV) at room temperature. Experimental data compare well with similar experiments performed by another group. The
conductivity spectrum of this conducting polymer has been deduced from the reflectivity spectrum by means of two methods,
Kramers-Kronig transformation and best fit of an “extended Drude” model to the reflectivity spectrum. Whereas the deviation
from Drude behavior was interpreted in terms of Anderson localization or by inhomogeneous disorder by other groups, it is
shown here that a different model developed for conducting oxides that also exhibit non-Drude behavior, applies very well
to this example of conducting polymer.
Received 11 February 1999 and Received in final form 26 April 1999 相似文献
18.
O. Wilhelmi K.-H. Schartner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,11(1):45-58
Ionisation and excitation of atomic oxygen in collisions with protons and electrons were studied experimentally in the intermediate
velocity range applying the method of fluorescence spectroscopy. Absolute emission cross-sections for 2s-electron ionisation, excited ion production and excitation of atomic oxygen are presented and for electron impact compared
to available data. For proton impact no emission cross-sections have been published so far.
Received 9 September 1999 and Received in final form 15 December 1999 相似文献
19.
J.C. Ewert G. Schmitz 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,17(3):391-403
A study of the reordering kinetics of ion-irradiated Ni3Al is presented. The development of long-range order during annealing treatments is measured by quantitative electron diffractometry.
According to the temperature dependence of the observed kinetics, the reaction is dominated by non-equilibrium vacancies.
As a consequence, the kinetics can be calibrated versus the absolute number of atomic jumps necessary to establish the observed degree of order. In order to analyse the experimental
data, Monte Carlo simulations are performed. It is shown that, beside the temperature dependence of the driving force, the
ordering efficiency of the vacancy jumps itself is temperature dependent due to different mobilities of the atomic species.
Received 6 December 1999 and Received in final form 23 June 2000 相似文献
20.
An infinite system of neutrons interacting by a model pair potential is considered. We investigate a case when this potential
is sufficiently strong attractive, so that its scattering length a tends to infinity, a
. It appeared, that if the structure of the potential is simple enough, including no finite parameters, reliable evidences
can be presented that such a system is completely unstable at any finite density. The incompressibility as a function of the
density is negative, reaching zero value when the density tends to zero. If the potential contains a sufficiently strong repulsive
core then the system possesses an equilibrium density. The main features of a theory describing such systems are considered.
Received: 17 December 1999 / Accepted: 23 December 1999 相似文献