共查询到20条相似文献,搜索用时 31 毫秒
1.
F.X. Gadéa Ph. Durand T. González-Lezana G. Delgado-Barrio P. Villarreal 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):215-219
The wave operator theory of quantum dynamics is applied to characterize coupled metastable states. The theory extends to quasi
bound states methods which are standard for dealing with bound levels. It is shown that interacting resonances can be investigated
by means of small-dimensional effective Hamiltonians containing all the significant information of intrinsic properties which
drive the various dynamical processes taking place. The study of the vibrational predissociation of I2Ne, mediated by intramolecular energy redistribution, illustrates the power of the method. In addition to its accuracy to
determine spectroscopic profiles and survival probabilities, it results more efficient than usual energy or time-domain numerical
calculations.
Received 25 January 2001 and Received in final form 11 May 2001 相似文献
2.
Y. Pavlyukh W. Hübner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,21(2):239-246
We present a method for the numerical investigation of the electron dynamics in small metallic clusters in intense laser fields.
We obtain information about collective excitations and relaxation processes in the Na
9
+
and Pt3 clusters analyzing the power spectrum of the dipole moment within a mean-field approach. The power spectrum is computed for
various laser pulse parameters as well as for the limit of an infinitely short laser pulse. Due to the basis set expansion
of the wave function our method is capable to follow the dynamics not only of the whole electron cloud, but of any particular
molecular orbital.
Received 28 March 2002 / Received in final form 31 May 2002 Published online 24 September 2002
RID="a"
ID="a"e-mail: pavlyukh@mpi-halle.de 相似文献
3.
B. Pilawa I. Keilhauer G. Fischer S. Knorr J. Rahmer A. Grupp 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(3):321-330
The magnetic properties of the cyclic compound [Fe6(bicine)6] LiClO4
. 2MeOH are reported. The cluster Fe6(bicine)6 forms an antiferromagnetically coupled ring structure of Fe III ions. The magnetic susceptibility is measured between 2 and 300 K and yields the exchange coupling of J/k
B = - 27.5±0.5 K. The field dependence of the magnetic moment is studied at 3 and 6 K in magnetic fields up to 5 T. The zero-field
splitting of the first excited spin states with S = 2 and 3 are determined by ESR at 94 GHz. The intra-molecular interactions of the Fe III ions are analyzed and the on-site anisotropy of the Fe III due to the ligand-configuration is determined to d /k
B = - 0.633±0.008K.
Received 28 October 2002 / Received in final form 22 February 2003 Published online 20 June 2003
RID="a"
ID="a"e-mail: bernd@piobelix.physik.uni-karlsruhe.de 相似文献
4.
Recent experiments have demonstrated that the dynamics in liquids close to the glass transition temperature is strongly heterogeneous.
The characteristic size of these heterogeneities has been measured to be a few nanometers at T
g. We extend here a recent model for describing the heterogeneous nature of the dynamics which allows both to derive this length
scale and the right orders of magnitude of the heterogeneities of the dynamics close to the glass transition. Our model allows
then to interpret quantitatively small probes diffusion experiments.
Received 29 March 2002 and Received in final form 11 November 2002
RID="a"
ID="a"e-mail: long@lps.u-psud.fr 相似文献
5.
C. Acha M. Monteverde M. Núñez-Regueiro A. Kuhn M. A. Alario Franco 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,32(4):421-428
The electronic and positronic properties of the pentanary semiconductor alloys GaxIn1-xPySbzAs1-y-z lattice matched to GaSb have been studied. The electron wave function is calculated semiempirically using the pseudopotential
band model under the virtual crystal approximation. The positron wave function is evaluated under the point core approximation
for the ionic potential. Electronic and positronic quantities namely, electronic structure and band gaps, positron band structure,
effective mass and affinity, and electron-positron momentum densities have been predicted and their dependence on the phosphorus
composition has been discussed.
Received 30 August 2002 / Received in final form 12 February 2003 Published online 24 April 2003 相似文献
6.
7.
M. Sakai S. Ishiuchi M. Fujii 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):399-402
The picosecond time-resolved IR spectrum of the 7-azaindole dimer has been measured by picosecond time-resolved nonresonant
ionization detected IR spectroscopy. This new time-resolved technique was developed by combining nonresonant ionization detected
IR (NID-IR) spectroscopy with tunable picosecond IR and UV lasers. The time-resolved NID-IR spectrum from 2 600 cm-1 to 3 800 cm-1 shows a drastic change from 1.5 ps to 11 ps time evolution. A mode-specific vibrational redistribution has been suggested.
Received 14 May 2002 / Received in final form 11 June 2002 Published online 13 September 2002 相似文献
8.
Zhenhong Dai Jinzuo Sun Lide Zhang Maowang Lu Zuohong Li Shiyong Huang 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(1):141-145
Artificial molecules, namely laterally coupled quantum dots with a three-dimensional spherical confinement potential well
of radius R and depth V
0, were studied by the unrestricted Hartree-Fock-Roothaan (UHFR) method. By varying the distance d between the centers of the two coupled quantum dots, the transition from the strong coupling situation to the weak one is
realized. Hund's rule, suitable for a single quantum dot is destroyed in certain conditions in the artificial molecule. For
example, in the few-electron system of the strongly coupled quantum-dot molecule, a transformation of spin configuration has
been found.
Received 8 March 2002 / Received in final form 29 May 2002 Published online 17 September 2002 相似文献
9.
H. Arkın T. Çelik 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):577-580
To investigate the performance of the energy landscape paving (ELP) procedure for peptides, we apply it here to deltorphin,
a linear heptapeptide with bulky side chains (H-Tyr1-D-Met2-Phe3-His4-Leu5-Met6-Asp7-NH2) and compare the results with the Multicanonical method (MUCA) in regard of finding the low-energy structures. Deltorphin
is modeled in vacuum by the potential energy function ECEPP.
Received 23 July 2002 / Received in final form 18 September 2002 Published online 31 December 2002 相似文献
10.
Cristóbal López Emilio Hernández-García 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,28(3):353-359
We study the influence of diffusion on the scaling properties of the first order structure function, S1, of a two-dimensional chaotically advected passive scalar with finite lifetime, i.e., with a decaying term in its evolution equation. We obtain an analytical expression for S1 where the dependence on the diffusivity, the decaying coefficient and the stirring due to the chaotic flow is explicitly
stated. We show that the presence of diffusion introduces a crossover length-scale, the diffusion scale (Ld), such that the scaling behaviour for the structure function is analytical for length-scales shorter than Ld, and shows a scaling exponent that depends on the decaying term and the mixing of the flow for larger scales. Therefore,
the scaling exponents for scales larger than Ld are not modified with respect to those calculated in the zero diffusion limit. Moreover, Ld turns out to be independent of the decaying coefficient, being its value the same as for the passive scalar with infinite
lifetime. Numerical results support our theoretical findings. Our analytical and numerical calculations rest upon the Feynmann-Kac
representation of the advection-reaction-diffusion partial differential equation.
Received 18 March 2002 Published online 31 July 2002 相似文献
11.
N. Shannon T. Chatterji F. Ouchni P. Thalmeier 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):287-297
We construct a theory of spin wave excitations in the bilayer manganite La1.2Sr1.8Mn2O7 based on the simplest possible double-exchange model, but including leading quantum corrections to the spin wave dispersion
and damping. Comparison is made with recent inelastic neutron scattering experiments. We find that quantum effects account
for some part of the measured damping of spin waves, but cannot by themselves explain the observed softening of spin waves
at the zone boundary. Furthermore a doping dependence of the total spin wave dispersion and the optical spin wave gap is predicted.
Received 15 January 2002 Published online 6 June 2002 相似文献
12.
N.A. Kostov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):255-259
We consider quasi-periodic and periodic (cnoidal) wave solutions of a set of n-component dynamical systems related to Korteweg-de Vries equation. Quasi-periodic wave solutions for these systems are expressed
in terms of Novikov polynomials. Periodic solutions in terms of Hermite polynomials and generalized Hermite polynomials for
dynamical systems related to Korteweg-de Vries equation are found.
Received 15 October 2001 / Received in final form 6 March 2002 Published online 2 October 2002
RID="a"
ID="a"e-mail: nakostov@ie.bas.bg 相似文献
13.
14.
A.V. Shtoff M. Rérat S.I. Gusarov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):199-208
Floquet theory is used to describe the response of a molecule to applied radiation electric field. The method of ab initio calculation of frequency dependent (hyper)polarizabilities based on combination of perturbation theory with the finite field
method has been developed. Electron correlation is taken into account by means of the CIPSI algorithm. The total wave function
expansion involves spectral, pseudo-spectral states and polynomial terms. The developed approach is applied to the calculation
of the second hyperpolarizability of the lithium hydride molecule subjected to the superposition of harmonic and static electric
fields. The method can be used to calculate the higher order nonlinear properties of molecules.
Received 23 November 2000 and Received in final form 25 March 2001 相似文献
15.
V. Baru J. Haidenbauer C. Hanhart J.A. Niskanen 《The European Physical Journal A - Hadrons and Nuclei》2003,16(3):437-446
We present a new parameterization of the trinucleon wave function. As a novel feature a separable parameterization for the
complete wave function is given. In this way any calculation that considers two-body currents only is largely simplified.
To demonstrate this we calculate the π3He scattering length in chiral-perturbation theory. We find reasonable agreement with experimental values inferred from data
on level shifts in pionic 3He bound states. The relevance of the π-triton system for an alternative determination of the πN scattering lengths is discussed.
Received: 12 August 2002 / Accepted: 25 November 2002 / Published online: 25 February 2003
RID="a"
ID="a"e-mail: c.hanhart@fz.juelich.de
Communicated by V. Vento 相似文献
16.
R. Yamamoto T. Ebata N. Mikami 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):403-408
Low frequency intermolecular vibrations of benzonitrile-(H2O)n = 1 - 3, -(CH3OH)n = 1 - 3, and -(CHCl3)n = 1 - 3 clusters were observed by stimulated Raman - UV double resonance spectroscopy combined with fluorescence detection. The Raman
active vibrations, which appear in the region from 5 to 50 cm-1, exhibit characteristic frequency shifts depending on the cluster structure and on the cluster size. In benzonitrile-(H2O)n = 1 - 3 and -(CH3OH)n = 1 - 3, the lowest frequency band showed a lower frequency shift with an increase of the number of solvent molecules. On the other
hand, that of benzonitrile-(CHCl3)n = 1 - 3 showed a shift to the higher frequency side. Their characteristic shifts are discussed based on the structure of the clusters.
Received 28 April 2002 / Received in final form 30 May 2002 Published online 13 September 2002 相似文献
17.
B. Leblanc E. Lutton F. Axel 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(4):619-628
We present the first application of Genetic Algorithms to the analysis of data from an aperiodically ordered system, high
resolution X-Ray diffraction spectra from multilayer heterostructures arranged according to a deterministic or random scheme.
This method paves the way to the solution of the “inverse problem”, that is the retrieval of the generating disorder from
the investigation of the spectra of an unknown sample having non crystallographic, non quasi-crystallographic order.
Received 18 March 2002 / Received in final form 3 July 2002 Published online 31 October 2002
RID="a"
ID="a"e-mail: Evelyne.Lutton@inria.fr
RID="b"
ID="b"CNRS UMR 8502 相似文献
18.
W. Christen U. Even 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):87-90
This contribution addresses the inelastic interaction of positively charged molecular cluster ions with a solid surface at
kinetic energies up to 30 eV/molecule. We report experimental results on the scattering of mass-selected, protonated methanol
cluster cations (CH3OH)nH+, n = 4-32, off a diamond-coated silicon surface. In particular we provide fragment size distributions of methanol cluster ions
following their impact on the target, as well as surface-induced neutralization probabilities of methanol cluster ions as
a function of the size and the kinetic energy of the parent clusters.
Received 30 November 2000 相似文献
19.
R. Xu Y.J. Yan O. Kühn 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(3):293-305
Separating multidimensional problems into that of a relevant system which is coupled to a bath of harmonic oscillators is
a common concept in condensed phase theory. Focusing on the specific problem of intramolecular proton transfer in an isolated
tropolone derivative, we consider the reactive proton moving in the plane of the molecule as the system and the remaining
substrate normal modes as the bath. An all-Cartesian system-plus-substrate Hamiltonian is constructed employing density functional
theory. It is then used to determine the temperature-dependent effective reduced reaction Hamiltonian and the state-to-state
dissipation rates induced via the system-substrate coupling up to the bi-quadratic order. The important substrate modes for the T1-relaxation and the pure T2-dephasing rates, which are either intra- or inter-well in nature, are identified numerically and analyzed physically with
molecular details.
Received 19 November 2001 and Received in final form 19 February 2002 相似文献
20.
Z. Iqbal Y. Zhang H. Grebel S. Vijayalakshmi A. Lahamer G. Benedek M. Bernasconi J. Cariboni I. Spagnolatti R. Sharma F.J. Owens M.E. Kozlov K.V. Rao M. Muhammed 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,31(4):509-515
Evidence is presented for the formation of a solid phase based on the smallest fullerene, C20, in thin diamond-like carbon films deposited by ultraviolet laser ablation from diamond onto nickel substrates at room temperature
in the presence of 10-4 torr of cyclohexane or benzene. Laser desorption mass spectrometry from the films shows the presence of C20, C21 and C22 species, while micro-Raman spectroscopy and electron diffraction from selected particles together with first principle density-functional
calculations, indicate a cubic solid with dodecahedral C20 cages as building blocks. Unlike solid C60 and fully protonated C20, which are bound by van der Waals forces, the proposed structure is stabilized by linking of the C20 dodecahedra with bridging carbon atoms at interstitial tetrahedral sites to form a face-centered-cubic lattice with 22 carbon
atoms per unit cell.
Received 10 October 2002 / Received in final form 24 December 2002 Published online 6 March 2003
RID="a"
ID="a"e-mail: zafar.iqbal@njit.edu 相似文献