共查询到20条相似文献,搜索用时 15 毫秒
1.
S. Velasco F.L. Román A. González J.A. White 《The European Physical Journal B - Condensed Matter and Complex Systems》1999,7(3):421-427
The study of a system of hard rods in a box of finite length in the presence of a uniform gravitational field is made by means
of the microcanonical ensemble. Explicit expressions are derived for the phase volume and the density of states, the primary
functions of this ensemble. Related statistical quantities are reported, such as the entropy, the temperature, the heat capacity
and the forces exerted on the fluid by the bottom and top walls. The microcanonical number density and higher order molecular
distribution functions are also derived.
Received: 7 April 1998 / Received in final form: 20 July 1998 / Accepted: 28 July 1998 相似文献
2.
F.J. Arranz F. Borondo R.M. Benito 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,4(2):181-187
Low resolution features in the spectra of classically chaotic atomic and molecular systems are known to be related to recurrences
induced by classical periodic motions. In this paper we study how such characteristics reveal in the LiNC/LiCN isomerizing
molecular system, and describe how the transition from regularity to classical chaos that takes place in this system shows
up at quantum level in the structure of the corresponding wavefunctions in the form of “scars”. To this end we use some projection
techniques, based on the propagation of wave packets, which have been developed in our laboratory. In this way some regions
at the border of the chaotic region can be detected, in which the systematics of “scar” formation can be studied at a very
elementary level, without complications due to the high level density which are customarily used in this type of studies in
order to achieve the semiclassical limit.
Received: 16 March 1998 / Revised: 23 April 1998 / Accepted: 4 May 1998 相似文献
3.
U. Hohenester P. Kocevar N.E. Hecker R. Rodrigues-Herzog 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(1):143-152
We present a systematic study of the dependence of the energy relaxation of photo-excited minority electrons on the doping
concentration in highly p-doped GaAs. A nonmonotonic dependence is found in the region where the characteristics of the carrier-carrier interaction
changes from plasmon-mediated to quasistatically screened. Using a detailed Monte-Carlo study we are able to attribute this
observation to a general property of plasmas at high density.
Received: 1st April 1998 / Revised: 6 May 1998 /
Accepted: 18 May 1998 相似文献
4.
Received: 14 April 1998/Accepted: 22 April 1998 相似文献
5.
J. Seres J. Klebniczki E. Seres J. Hebling 《Applied physics. B, Lasers and optics》1998,67(5):569-572
Received: 1 April 1998/Revised version: 20 April 1998 相似文献
6.
Mid-infrared spectroscopic detection of trace gases using guided-wave difference-frequency generation 总被引:1,自引:0,他引:1
K.P. Petrov A.T. Ryan T.L. Patterson L. Huang S.J. Field D.J. Bamford 《Applied physics. B, Lasers and optics》1998,67(3):357-361
Received: 1 April 1998/Revised version: 29 April 1998 相似文献
7.
V.G. Rostiashvili M. Rehkopf T.A. Vilgis 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(2):233-243
In this paper the Martin-Siggia-Rose (MSR) functional integral representation is used for the study of the Langevin dynamics
of a polymer melt in terms of collective variables: mass density and response field density. The resulting generating functional
(GF) takes into account fluctuations around the random phase approximation (RPA) up to an arbitrary order. The set of equations
for the correlation and response functions is derived. It is generally shown that for cases whenever the fluctuation-dissipation
theorem (FDT) holds we arrive at equations similar to those derived by Mori-Zwanzig. The case when FDT in the glassy phase
is violated is also qualitatively considered and it is shown that this results in a smearing out of the ideal glass transition.
The memory kernel is specified for the ideal glass transition as a sum of all “water-melon” diagrams. For the Gaussian chain
model the explicit expression for the memory kernel was obtained and discussed in a qualitative link to the mode-coupling
equation.
Received: 9 January 1998 / Revised: 24 April 1998 / Accepted: 2 July 1998 相似文献
8.
H. Jantoljak J.-P. Salvetat L. Forró C. Thomsen 《Applied Physics A: Materials Science & Processing》1998,67(1):113-116
Received: 8 April 1998/Accepted: 9 April 1998 相似文献
9.
S. Guha 《Applied physics. B, Lasers and optics》1998,66(6):663-675
Received: 15 February 1998/Revised version: 6 April 1998 相似文献
10.
A. Lange M. Schröter M.A. Scherer A. Engel I. Rehberg 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(4):475-484
The temporal evolution of a water-sand interface driven by gravity is experimentally investigated. By means of a Fourier analysis
of the evolving interface the growth rates are determined for the different modes appearing in the developing front. To model
the observed behavior we apply the idea of the Rayleigh-Taylor instability for two stratified fluids. Carrying out a linear
stability analysis we calculate the growth rates from the corresponding dispersion relations for finite and infinite cell
sizes. Based on the theoretical results the viscosity of the suspension is estimated to be approximately 100 times higher
than that of pure water, in agreement with other experimental findings.
Received: 12 December 1997 / Revised: 23 March 1998 / Accepted: 28
April 1998 相似文献
11.
G. Modugno C. Corsi M. Gabrysch F. Marin M. Inguscio 《Applied physics. B, Lasers and optics》1998,67(3):289-296
2 , and its sensitivity is 7(2)×10-8 in a 1-Hz bandwidth. The corresponding minimum detectable concentration of CO2 in air has been estimated to be 1 ppm · m. This opens the possibility of a detection at ppb levels at 2 μm, where a two orders
of magnitude increase in the CO2 absorption signal is demonstrated.
Received: 06 April 1998/Revised version: 02 July 1998 相似文献
12.
W. Michalke S. Kreitmeier 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,4(4):469-473
The diffusion Quantum-Monte-Carlo method of solving the Schr?dinger equation is applied to the vibrational ground state of
a polyethylene molecule. The results for the ground state energy show good agreement with normal mode analysis. In addition
to stretching, bending and torsional interaction van-der-Waals interaction is applied to a single chain showing a decrease
of the energy of 5%. The decrease for a polyethylene system of 5 chains with 10 atoms per molecule at the positions of a unit
cell is determined to be 4.8% per molecule. Finally first steps towards simulating excited states were performed.
Received: 9 February 1998 / Revised: 2 April 1998 / Accepted: 23 April 1998 相似文献
13.
K. Totsuka 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(3):705-717
Novel massive quantum states appearing in spin chains under a strong magnetic field are discussed. These states lead to plateaus in magnetization
curves. When the systems are axially symmetric and the field is applied parallel to the symmetry-axis, the phenomena are analogous
to metal-insulator transitions. Striking features of the plateau phenomena - exactness and rationality - are explained as
consequences the commensurability condition to the underlying lattice. The effects of the planar anisotropy are also discussed
in detail.
Received: 16 February 1998 / Revised: 20 April 1998 / Accepted: 30 April 1998 相似文献
14.
Received: 14 April 1998/Accepted: 23 October 1998 相似文献
15.
S. Tosto 《Applied Physics A: Materials Science & Processing》1999,68(4):439-446
Received: 21 April 1998 / Accepted: 21 September 1998 / Published online: 24 February 1999 相似文献
16.
J. Boneberg H.-J. Münzer M. Tresp M. Ochmann P. Leiderer 《Applied Physics A: Materials Science & Processing》1998,67(4):381-384
Received: 20 April 1998/Accepted: 2 June 1998 相似文献
17.
M. Henkel D. Karevski 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(3):787-792
The effect of point defects on persistent currents in mesoscopic rings is studied in a simple tight-binding model. Using an
analogy with the treatment of the critical quantum Ising chain with defects, conformal invariance techniques are employed
to relate the persistent current amplitude to the Hamiltonian spectrum just above the Fermi energy. From this, the dependence
of the current on the magnetic flux is found exactly for a ring with one or two point defects. The effect of an aperiodic
modulation of the ring, generated through a binary substitution sequence, on the persistent current is also studied. The flux-dependence
of the current is found to vary remarkably between the Fibonacci and the Thue-Morse sequences.
Received: 4 March 1998 / Revised: 20 April 1998 / Accepted: 30 April 1998 相似文献
18.
D. Chowdhury A. Pasupathy S. Sinha 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(3):781-786
In the Nagel-Schreckenberg model of vehicular traffic on single-lane highways vehicles are modelled as particles which hop
forward from one site to another on a one dimensional lattice and the inter-particle interactions mimic the manner in which
the real vehicles influence each other's motion. In this model the number of empty lattice sites in front of a particle is
taken to be a measure of the corresponding distance-headway (DH). The time-headway (TH) is defined as the time interval between the departures (or arrivals) of two successive particles recorded by a detector
placed at a fixed position on the model highway. We investigate the effects of spatial inhomogeneities of the highway (static
hindrances) on the DH and TH distributions in the steady-state of this model.
Received: 2 March 1988 / Revised: 13 April 1998 / Accepted: 17 April 1998 相似文献
19.
A. Trovato J. van Mourik A. Maritan 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(1):63-73
A lattice model of a hetero-polymer with random hydrophilic-hydrophobic charges interacting with the solvent is introduced,
whose continuum counterpart has been proposed by Garel, Leibler and Orland [#!GLO!#]. The transfer matrix technique is used
to study various constrained annealed systems which approximate at various degrees of accuracy the original quenched model.
For highly hydrophobic chains an ordinary -point transition is found from a high temperature swollen phase to a low temperature compact phase. Depending on the type
of constrained averages, at very low temperatures a swollen phase or a coexistence between compact and swollen phases are
found. The results are carefully compared with the corresponding ones obtained in the continuum limit, and various improvements
in the original calculations are discussed.
Received: 10 April 1998 / Revised: 4 June 1998 / Accepted: 1st July 1998 相似文献
20.
A. Montorsi 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,5(3):419-422
We investigate under which circumstances extended Hubbard models, including bond-charge, exchange, and pair-hopping terms,
are invariant under gl
(2,1) superalgebra. This happens for a two-parameter Hamiltonian which includes as particular cases the t
-
J, the EKS and the one-parameter BGLZ Hamiltonians, all integrable in one dimension. We show that the two parameter Hamiltonian
can be recasted as the sum of the BGLZ Hamiltonian plus the graded permutation operator of electronic states on neighbouring
sites. The integrability of the corresponding one-dimensional model is discussed.
Received: 17 February 1998 / Received in final form: 6 March 1998 / Accepted: 17 April 1998 相似文献