共查询到20条相似文献,搜索用时 31 毫秒
1.
F.X. Gadéa T. Leininger A.S. Dickinson 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):251-255
An improved ab initio calculation has been performed for the potential for the LiH a 3Σ+ state, using two very large basis sets. The Basis Set Superposition Error (BSSE) correction has been determined for both
basis sets and the non-Born-Oppenheimer correction estimated to be negligible. The best potential is approximately 10% deeper
than the previous estimate. Vibrational energies and scattering lengths have been calculated for 6,7LiH(D) with both potentials, with and without the BSSE correction, and also with an estimated potential expected to bracket
the true potential. The 7LiH scattering length is estimated to be (45 ± 4)a0 and hence the low-energy cross-section in the best a 3Σ+ potential is about half that calculated previously. Enhanced cooling by 7Li of trapped H atoms remains feasible.
Received 30 April 2001 相似文献
2.
Inclusions embedded in lipid membranes undergo a mediated force, due to the tendency of the membrane to relax its excess of
elastic energy. In this paper we determine the exact shape of a two-dimensional vesicle hosting two different inclusions,
and we analyse how the inclusion conformation influences the mediated interaction. We find non-trivial equilibrium configurations
for the inclusions along the hosting membrane, and we derive the complete phase diagram of the mediated interaction. In particular,
we find a non-vanishing mediated force even when the distance between the inclusions is much greater than their size. Our
model can be applied to describe the mediated interactions of parallel, elongated inclusions embedded in three-dimensional
membranes.
Received 22 October 2001 and Received in final form 8 March 2002 相似文献
3.
E. Czuchaj M. Kronicki J. Czub 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(3):345-353
Excitation spectra arising from A
3
0
+
←
X
1
0
+
and B
3
1 ←
X
1
0
+
electronic transitions in the Cd-rare gas (RG) van der Waals molecules are calculated using newly obtained theoretical potential
curves for these species. In the molecular structure calculations, Cd20+ and RG8+ cores are simulated by energy-consistent pseudopotentials which also account for scalar-relativistic effects and spin-orbit
(SO) interaction within the valence shell. Potential energies in the Λ
S coupling scheme have been obtained by means of ab initio complete-active-space multiconfiguration self consistent-field (CASSCF)/complete-active-space multireference second-order
perturbation theory (CASPT2) calculations with a total 28 correlated electrons, while the SO matrix has been computed in a
reduced CI space restricted to the CASSCF level. The final Ω potential curves are obtained by diagonalization of the modified SO matrix (its diagonal elements before diagonalization
substituted for the corresponding CASPT2 eigen-energies). The spectroscopic parameters for the ground and several excited
states of the Cd-RG complexes deduced from the calculated potential curves are in quite reasonable agreement with available
experimental data. In addition, the radial Schr?dinger equation for nuclear motion was solved numerically with the calculated
potentials to evaluate the corresponding vibrational levels and radial wavefunctions. The latter have been used in the calculation
of the appropriate Franck-Condon factors to yield information on relative intensities of the vibrational bands of the Cd-RG
complexes. The theoretical vibrational progressions are discussed in the context of experimental spectra.
Received 10 August 2000 and Received in final form 7 November 2000 相似文献
4.
M. Boström J.J. Longdell D.J. Mitchell B.W. Ninham 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(1):47-52
The nature of the resonance interaction between two isotropic atoms in an excited configuration is reinvestigated. The currently
accepted oscillatory form for the long-range retarded resonance interaction is shown to be a subtle artefact that arises due
to too drastic approximations. Formulation of the resonance interaction energy problem in terms of the interacting system leads to a form that it is ∝ r
-4 in the retarded limit. We also demonstrate that the resonance interaction energy at any finite temperature goes over to purely
classical long-range asymptote. This manifestation of the correspondence principle is due to thermal excitation of the electromagnetic
field. We finally discuss why the textbook result for the F?rster energy transfer between two atoms is incorrect for the same
reasons.
Received 31 January 2002 / Received in final form 25 July 2002 Published online 29 October 2002
RID="a"
ID="a"e-mail: mtb110@rsphysse.anu.edu.au 相似文献
5.
Steven C. Pieper 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):75-79
Quantum Monte Carlo calculations using realistic two- and three-nucleon interactions are presented for nuclei with up to ten
nucleons. Our Green's function Monte Carlo calculations are accurate to ∼1-2% for the binding energy. We have constructed
Hamiltonians using the Argonne v18
NN interaction and reasonable three-nucleon interactions that reproduce the energies of these nuclear states with only ∼500
keV rms error. Other predictions, such as form factors, decay rates, and spectroscopic factors also agree well with data.
Some of these results are presented to show that ab initio calculations of light nuclei are now well in hand.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
6.
R. Beuc H. Skenderovi T. Ban D. Vea G. Pichler W. Meyer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(2):209-214
We measured a very distinct satellite band at 875.2 nm between two resonance lines of cesium. Spectral simulation using Spies
and Meyer [#!ref1!#] ab initio potential curves and an appropriate transition dipole moment function was compared with experimental profile. Implications
of the investigated satellite band at 875.2 nm in the field of ultracold cesium atom collisions are discussed with a special
emphasize to new possibilities of the photoassociation of two ground state atoms leading to the formation of ultracold intermediate
long-range molecules.
Received 07 March 2001 and Received in final form 14 May 2001 相似文献
7.
The Dirac structure of the nucleon self-energy in symmetric nuclear matter as well as neutron matter is derived from a realistic
meson exchange model for the nucleon-nucleon (NN) interaction. It is demonstrated that the effects of correlations on the
effective NN interaction in the nuclear medium can be parameterized by means of an effective meson exchange. This analysis
leads to a very intuitive interpretation of correlation effects and also provides an efficient parametrization of an effective
interaction to be used in relativistic structure calculations for finite nuclei.
Received: 29 January 2001 / Accepted: 5 May 2001 相似文献
8.
H. Skenderović R. Beuc T. Ban G. Pichler 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):49-56
Three distinct satellite bands at 730-736 nm and a single shoulder at 755.5 nm that we assigned to KRb heteronuclear molecule
are found in absorption measurements of hot K + Rb vapor. The interpretation of these bands is discussed in terms of recent
ab initio calculations of the relevant potential curves. Semiclassical spectral simulations were performed with ab initio potentials and approximate transition dipole moment functions showing a good agreement with observations. The probabilities
of cold molecule photoassociative formation into the external well of the double minimum (5)0+ state and decay to the ground state are discussed, and relative yields of molecular formation were estimated by using quantum
mechanical calculations.
Received 15 October 2001 相似文献
9.
G. Benenti G. Casati D.L. Shepelyansky 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):265-272
We model an isolated quantum computer as a two-dimensional lattice of qubits (spin halves) with fluctuations in individual
qubit energies and residual short-range inter-qubit couplings. In the limit when fluctuations and couplings are small compared
to the one-qubit energy spacing, the spectrum has a band structure and we study the quantum computer core (central band) with
the highest density of states. Above a critical inter-qubit coupling strength, quantum chaos sets in, leading to quantum ergodicity
of eigenstates in an isolated quantum computer. The onset of chaos results in the interaction induced dynamical thermalization
and the occupation numbers well described by the Fermi-Dirac distribution. This thermalization destroys the noninteracting
qubit structure and sets serious requirements for the quantum computer operability.
Received 3 July 2001 and Received in final form 9 September 2001 相似文献
10.
M. Modugno C. Fort P. Maddaloni F. Minardi M. Inguscio 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):345-349
We have investigated the center-of-mass oscillations of a 87Rb Bose-Einstein condensate in an elongated magneto-static trap. We start from a trapped condensate and we transfer part of
the atoms to another trapped level, by applying a radio-frequency pulse. The new condensate is produced far from its equilibrium
position in the magnetic potential, and periodically collides with the parent condensate. We discuss how both the damping
and the frequency shift of the oscillations are affected by the mutual interaction between the two condensates, in a wide
range of trapping frequencies. The experimental data are compared with the prediction of a mean-field model.
Received 28 May 2001 相似文献
11.
T.A. Beu J. Onoe K. Takeuchi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(2):205-212
Non-orthogonal tight-binding molecular-dynamics is employed to calculate structural and vibrational properties of C36 and its oligomers (C36)
M = 2, 3, 4
. The lowest energy configuration of the C
36
cage is confirmed to have D
6h
symmetry. For the dimer, too, the D
2h
structure reported in the literature is found. The vibrational spectrum is identified with the power spectrum of the displacement
autocorrelation function. Additional vibrational properties are extracted from the dynamical matrix. For the monomer, fair
agreement with available ab initio calculations is achieved, with comparatively smaller deviations in the Raman-frequencies than for published semi-empirical
calculations. The features of the vibrational modes are correlated with the structural properties of the oligomers.
Received 24 November 2000 and Received in final form 24 August 2001 相似文献
12.
13.
B. Pasquini M. Gorchtein D. Drechsel A. Metz M. Vanderhaeghen 《The European Physical Journal A - Hadrons and Nuclei》2001,11(2):185-208
We present in detail a dispersion relation formalism for virtual Compton scattering (VCS) off the proton from threshold into
the Δ(1232)-resonance region. Such a formalism can be used as a tool to extract the generalized polarizabilities of the proton
from both unpolarized and polarized VCS observables over a larger energy range. We present calculations for existing and forthcoming
VCS experiments and demonstrate that the VCS observables in the energy region between pion production threshold and the Δ(1232)-resonance
show an enhanced sensitivity to the generalized polarizabilities.
Received: 14 March 2001 / Accepted: 18 June 2001 相似文献
14.
A. Bielski D. Lisak R.S. Trawiński J. Szudy 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):217-222
Using a laser-induced fluorescence method a detailed analysis of profiles of the 114Cd 326.1 nm line perturbed by N2 and CH4 was performed which revealed deviations from the ordinary Voigt profile. These deviations are shown to be consistent with
fits of experimental profiles to an asymmetric Voigt profile. Coefficients of the pressure broadening, shift and collision-time
asymmetry are determined and compared with those calculated for van der Waals interaction potential.
Received 29 November 2001 / Received in final form 12 July 2002 Published online 4 February 2003 相似文献
15.
G.K. Paramonov H. Naundorf O. Kühn 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,14(2):205-215
The laser driven dynamics of the OH(D) stretching vibration in phthalic acid monomethylester is investigated. The combination
of a 55-dimensional all-Cartesian reaction surface Hamiltonian and the time-dependent self-consistent field approach is shown
to provide a microscopic picture of intramolecular vibrational energy redistribution taking place upon interaction with an
external laser field. Choosing suitable zeroth-order vibrational states and combinations thereof a quasi-periodic in-phase and out-of-phase oscillatory behavior is observed manifesting energy flow on different time scales. The fingerprints of this behavior in transient
absorption spectroscopy are also discussed.
Received 24 August 2000 and Received in final form 11 October 2000 相似文献
16.
K. Fan J. Wang W. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(3):381-391
We propose a modified Gō model in which the pairwise interaction energies vary as local environment changes. The stability
difference between the surface and the core is also well considered in this model. Thermodynamic and kinetic studies suggest
that this model has improved folding cooperativity and foldability in contrast with the Gō model. The free energy landscape
of this model has broad barriers and narrow denatured states, which is consistent with that of the two-state folding proteins
and is lacked for the Gō model. The role of non-native interactions in protein folding is also studied. We find that appropriate
consideration of the contribution of the non-native interactions may increase the folding rate around the transition temperature.
Our results show that conformation-dependent interaction between the residues is a realistic representation of potential functions
in protein folding.
Received 10 April 2002 / Received in final form 20 August 2002
Published online 19 December 2002
RID="a"
ID="a"e-mail: wangwei@nju.edu.cn 相似文献
17.
S. Leoni A. Bracco T. Døssing B. Herskind J.C. Lisle M. Matsuo E. Vigezzi J. Wrzesinski 《The European Physical Journal A - Hadrons and Nuclei》1999,4(3):229-231
The number of discrete rotational bands in the nucleus 168Yb is obtained by a fluctuation analysis of the rotational ridge structure in double and triple γ coincidence matrices. The
data are compared with cranked shell model calculations including a surface delta interaction. It is found that the number
of calculated bands strongly depends on the interaction strength V0, and agreement between data and calculations supports the standard value V0= 27.5/A MeV.
Received: 11 January 1999 相似文献
18.
U. Kentsch T. Werner G. Zschornack F. Grossmann V.P. Ovsyannikov F. Ullmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,17(3):297-305
Irq+ ( 41≤q≤64) ions with open-shell configurations have been produced in the electron beam of the room-temperature Dresden Electron
Beam Ion Trap (Dresden EBIT) at electron excitation energies from 2 keV to 13 keV. X-ray emission from direct excitation processes
and radiative capture in krypton-like to aluminium-like iridium ions is measured with an energy dispersive Si(Li) detector.
The detected X-ray lines are analyzed and compared with results from multiconfigurational Dirac-Fock (MCDF) atomic structure
calculations. This allows to determine dominant produced ion charge states at different electron energies. The analysis shows
that at the realized working gas pressure of 5×10-9mbar for higher charged ions the maximum ion charge state is not preferently determined by the chosen electron beam energy
needed for ionization of certain atomic substates, but by the balance between ionization and charge state reducing processes
as charge exchange and radiative recombination. This behaviour is also discussed on the basis of model calculations for the
resulting ion charge state distribution.
Received 12 July 2001 and Received in final form 10 September 2001 相似文献
19.
I. Hamamoto 《The European Physical Journal A - Hadrons and Nuclei》2002,13(1-2):21-26
Nucleons with very small binding energies present in nuclei far from the β stability line produce a unique shell structure,
which leads to the disappearance of traditional magic numbers or to the creation of new magic numbers and new deformation
regions. We study the shell structure in terms of the variation of two important ingredients, the kinetic energy and the spin-orbit
splitting, as a function of the orbital angular momentum ℓ, when binding energies of neutrons decrease towards zero. It is
also shown that for low-lying threshold strength, a negative sign is possible for the polarization charge coming from the
coupling of one-particle to isoscalar shape oscillations.
Received: 1 May 2001 / Accepted: 4 December 2001 相似文献
20.
F.J. García-Vidal J.M. Pitarke 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,22(2):257-265
Optical-absorption cross-sections and energy-loss spectra of aligned multishell carbon nanotubes are investigated, on the
basis of photonic band-structure calculations. A local graphite-like dielectric tensor is assigned to every point of the tubules,
and the effective transverse dielectric function of the composite is computed by solving Maxwell's equations in media with
tensor-like dielectric functions. A Maxwell-Garnett-like approach appropriate to the case of infinitely long anisotropic tubules
is also developed. Our full calculations indicate that the experimentally measured macroscopic dielectric function of carbon
nanotube materials is the result of a strong electromagnetic coupling between the tubes. An analysis of the electric-field
pattern associated with this coupling is presented, showing that in the close-packed regime the incident radiation excites
a very localized tangential surface plasmon.
Received 18 January 2001 相似文献