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1.
S. Zschocke G. Plunien G. Soff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(2):147-156
The renormalization method of Bogoljubov-Parasiuk-Hepp-Zimmermann (BPHZ) is used in order to derive the renormalized energy
shift due to the gauge invariant K?llén-Sabry diagram of the two-photon vacuum polarization (VPVP) as well as the self energy
vacuum polarization S(VP)E beyond the Uehling approximation. It is outlined, that no outer renormalization is required for
the two-photon vacuum polarization and that only the inner renormalization has to be accomplished. It is shown that the so-called
nongauge invariant spurious term is absent for a wide class of vacuum polarization (VP) diagrams if one applies the widely
used spherical expansion of bound and free-electron propagator. This simplifies significantly calculations in bound state
quantum electrodynamics. As one result of our paper the use of the BPHZ-approach in bound state QED is established.
Received 28 September 2001 相似文献
2.
M. Bertolus V. Brenner P. Millié 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,1(2):197-205
A theoretical study of clusters with using density functional theory is presented. Tests of various functionals demonstrate that local spin density approximation
(LSDA) is the most adequate functional for the study of these systems. Structures, vibrational frequencies, and IR intensities
of the lowest energy isomer of the studied clusters obtained using LSDA are described, and the unusual properties of the Si-C
clusters are discussed. A quantitative analysis of the obtained structures was carried out, and relations between the coordinations,
interatomic distances, and angles observed in the Si-C clusters were obtained through introduction of the notion of coordination.
This analysis also shows that the carbon atoms mainly exhibit sp and sp2 hybridizations, and that a majority of silicon atoms do not hybridize. This study is the fi
rst step of the implementation of a semi-empirical potential, which would describe the moderately small Si-C clusters.
Received: 20 October 1997 / Received in final form: 16 December 1997 / Accepted: 17 December 1997 相似文献
3.
S. Neukermans N. Veldeman E. Janssens P. Lievens Z. Chen P.v.R. Schleyer 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):301-308
We report a combined experimental and computational
investigation of small AlnOm species (n ≤20, m ≤
12), produced in a laser vaporization cluster source. The oxygen
content in the clusters was tuned by varying the oxygen
concentration in the carrier gas. Ionization energies are
bracketed using different ionizing photon energies in the energy
range between 5.37 and 7.89 eV. Among the singly doped AlnO
species, Al3O and Al15O are found to have relatively low
ionization energies, which can be related to the magic character
of the corresponding cations. Peculiarly low ionization energies
also are observed for specific oxygen rich species (m > 1),
suggesting the formation of ionically bound subunits. The
structures and ionization energies of singly doped AlnO0,+
(n = 1 - 7) clusters were determined using density functional
theory (B3LYP/6-311+G(d)).
Electronic supplementary material Supplementary Online Material 相似文献
4.
A.V. Volotka V.M. Shabaev G. Plunien G. Soff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(1):51-56
The finite nuclear size effect on the hyperfine splitting of low-Z hydrogen-like atoms is studied in the external field approximation. A simple non-relativistic formula is proposed which expresses
the nuclear size correction to the hyperfine splitting in terms of moments of the nuclear charge and magnetization distribution.
The numerical results obtained via this formula are compared with corresponding results derived by means of the Zemach formula. A relativistic formula for the
nuclear size correction to the hyperfine splitting is also derived.
Received 18 March 2002 / Received in final form 14 November 2002 Published online 28 January 2003
RID="a"
ID="a"e-mail: plunien@physik.tu-dresden.de 相似文献
5.
V. V. Bondarchuk I. M. Shvab 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,42(3):381-386
With the help of perturbation theory the asymptotic
expansions (at small and large internuclear distances R) of the
eigenvalues (potential curves) E(R) of the two-Coulomb-centre
problem in 2+1 dimensions are obtained. We compare the results
obtained with the data from similar approximation for
two-Coulomb-centre problem in 3+1 dimensions. 相似文献
6.
A. Borschevsky E. Eliav M. J. Vilkas Y. Ishikawa U. Kaldor 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(1):115-119
Transition energies of the superheavy element lawrencium, including the ionization potential, excitation energies and electron
affinities, are calculated by the intermediate Hamiltonian coupled cluster method. A large basis set (37s31p26d21f16g11h6i)
is used, as well as an extensive P space (6s5p4d2f1g). The outer 43 electrons are correlated. Accuracy is monitored by applying
the same approach to lutetium, the lighter homologue of Lr, and comparing with experimentally known energies. QED corrections
are
included. The main goal is to predict excitation energies, in anticipation of planned spectroscopy of Lr.
The ground state of Lr is
, unlike the
of Lu. Predicted Lr excitations with large transition moments in the prime range for the planned experiment, 20 000–30 000 cm-1, are 7p→8s at 20 100 cm-1
and 7p→7d at 28 100 cm-1. The average absolute
error of 20 excitation energies of Lu is 423 cm -1, and the error limits for Lr are put at 700 cm-1.
The two electron affinities measured recently for Lu are reproduced within 55 cm-1, and a third bound state of Lu- is predicted. 相似文献
7.
S. G. Karshenboim V. G. Ivanov E. Yu. Korzinin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,39(3):351-358
In muonic atoms the Uehling potential (an effect of a
free electronic vacuum polarization loop) is responsible for the
leading contribution to the Lamb shift causing the splitting of
states with Δn=0 and Δl≠0. Here we consider the
Lamb shift in the leading nonrelativistic approximation, i.e.,
within an approach based on a certain Schr?dinger equation. That
is valid for low and medium Z as long as (Zα)2≪1. The
result is a function of a few parameters, including
κ=Zαmμ/me, n and l. We present various
asymptotics and in particular we study a region of validity of
asymptotics with large and small κ. Special attention is
paid to circular states, which are considered in a limit of
n≫1. 相似文献
8.
9.
Z.-C. Yan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(1):15-18
The fully correlated calculations of the Zeeman gJ factors for the first three quartet S states of lithium are presented, including relativistic and radiative corrections of
orders α2, α2
m/M, and α3. The isotope shifts in gJ are predicted precisely for various isotopes of lithium.
Received 4 December 2000 and Received in final form 26 September 2001 相似文献
10.
R. L. Zhou B. C. Pan 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,47(3):367-372
We extensively search for the endohedral silicon-fullerene
structures of Si31–Si39 using the combination of a
tight-binding potential with the density functional theory. The
resulting structures of our best candidates characterize more
compact features comparing to previous isomers [J. Am. Chem. Soc. 126, 13845 (2004); J. Chem. Phys. 124, 164311 (2006)]. Most of our best candidates belong to new families
featuring different core/cage combinations or different original
carbon fullerene cages with respect to those of previous isomers.
Energy calculations reveal that our best candidates are more
stable than the previous best ones at the PW91 level, except for
n = 34 and 38. The predicted relative stabilities of these isomers remain even at finite
temperatures. In addition, the densities of dangling-bond atoms in
the surfaces of our Si33 and Si39 isomers are
significantly lower than the previous best candidates, as well as
lower than those of their neighbors. This finding together with
the densities of the active sites in the surfaces of the previous best candidates
of Si34 and Si38 is roughly consistent with the observed relative reactivities of the silicon
clusters in the size range of n = 31-39. 相似文献
11.
12.
G. Durand F. Spiegelmann 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(2):237-243
The stability against fragmentation and possible relaxation of the lowest excited states of the Na5F4 cluster (representative of cubic non stoechiometric clusters with an excess sodium atom, also called sodium-tail) is investigated
by means of one-electron pseudopotential calculations with particular reference to photoabsorption processes from the ground
state. Whereas the equilibrium configuration of the ground state has C3v symmetry, the doubly degenerate 12E excited state is affected by a conical intersection and a Jahn-Teller effect associated with the rotation of the sodium
tail around the C3-axis. This yields a “Mexican hat" topology for the lowest sheet with three equivalent Cs minima. Alternatively the 22A1 state has a minimum retaining the C3v symmetry. The dissociation paths of the cluster along the C3-axis into respectively Na4F4 + Na and Na4F3 + NaF are also investigated. Among the former paths, the excited states are found adiabatically stable with respect to the
products. However in the A1 symmetry, fragmentation into NaF exhibits an interesting avoided crossing between configurations correlated respectively
with Na4F3
+ + NaF- and Na4F3 + NaF. Such interaction, similar to the well-known charge exchange processes in elementary molecules might induce non adiabatic
predissociation of the 22A1 state. This mechanism is invoked to explain the differences between R2PI and depletion spectra, correlated with the dissociation
or relaxation of the excited states.
Received 24 March 2000 and Received in final form 11 July 2000 相似文献
13.
S. Karshenboim U. Jentschura V. Ivanov G. Soff 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,2(3):209-215
We present an analytical evaluation of radiative corrections in exotic atoms induced by the one-loop electronic vacuum polarization.
We evaluate corrections to the energy levels, to the wave function (at the origin) and to the hyperfine structure. We treat
all corrections analytically within a non-relativistic approximation. Agreement is found with a few available numerical results.
The analytical treatment allows to determine the asymptotic forms of the corrections in the limit of a small atomic radius,
which for the atomic systems considered corresponds to a large mass of the constituent particle as compared to the electron
mass. The asymptotics can be verified using the effective charge approach.
Received: 28 January 1998 / Accepted: 13 March 1998 相似文献
14.
S. G. Karshenboim V. G. Ivanov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,19(1):13-23
We consider hyperfine splitting of 1s and, in part, of 2s levels in light hydrogen-like atoms: hydrogen, deuterium, tritium, helium-3 ion, muonium and positronium. We discuss present
status of precision theory and experiment for the hfs intervals. We pay a special attention to a specific difference, D
21 = 8E
hfs(2s) - E
hfs(1s), which is known experimentally for hydrogen, deuterium and 3
He
+ ion. The difference is weakly affected by the effects of the nuclear structure and thus may be calculated with a high accuracy.
We complete a calculation of the fourth order QED contributions to this difference and present here new results on corrections due to the nuclear effects. Our theoretical
predictions appear to be in a fair agreement with available experimental data. Comparison of the experimental data with our
examination of D21 allows to test the state-dependent sector of theory of the hfs separation of the 1s and 2s levels in the light hydrogen-like atoms up to 10-8.
Received 22 September 2001 相似文献
15.
A. V. Volotka D. A. Glazov G. Plunien V. M. Shabaev I. I. Tupitsyn 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):293-298
The one-electron quantum-electrodynamic corrections to the
magnetic-dipole transition amplitude
between the fine-structure
levels (1s2 2s2 2p) 2P3/2 - 2P1/2 in boronlike ions
are calculated to all orders in αZ. The results obtained
serve for improving the theoretical accuracy of the lifetime of the
(1s2 2s2 2p) 2P3/2 level in boronlike argon. 相似文献
16.
G. Chen Z.F. Liu X.G. Gong 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):33-36
We have studied the atomic structure and the electronic properties of Ban clusters by the ab initio molecular dynamics method. We find that a structural transition to the bulk-like structure begins at Ba9 cluster, and the structures of the clusters are transferred to be icosahedral-like around n
= 13. The relatively high stability for Ba4, Ba10 and Ba13 clusters are observed.
Received 1st December 2000 相似文献
17.
T. Beier H. Häffner N. Hermanspahn S. Djekic H.-J. Kluge W. Quint S. Stahl T. Valenzuela J. Verdú G. Werth 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):41-44
We describe a double-Penning-trap experiment suitable for testing QED in strong fields by determining the electronic g-factor of a single hydrogen-like ion in its ground state. Our measurements on 12C5 + reach a relative accuracy of 2×10-9, where the largest uncertainty results from the mass of the electron. Together with equally precise theoretical predictions
therefore, it is possible to evaluate a new value for the electron's mass. The possibilities to obtain other fundamental constants
and nuclear parameters are lined out.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: t.beier@gsi.de 相似文献
18.
J.P. Santos F. Parente P. Indelicato 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1998,3(1):43-52
A theoretical study of the one- and two-photon spontaneous emission rates from the 2
s1/2 state of one-electron ions is presented. High-precision values of the relativistic emission rates for ions with nuclear charge
Z up to 100 are obtained through the use of finite basis sets for the Dirac equation constructed from B-splines. Furthermore,
we analyze the influence of the inclusion of quantum electrodynamics corrections in the initial and final state energies.
Received: 6 January 1998 / Accepted: 31 March 1998 相似文献
19.
J. Moc 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,45(2):247-252
Five doublet isomers of the Al3H2 cluster lying
within a narrow range of 5 kcal/mol, along with the isomerization transition
states connecting them, have been located with the coupled-cluster CCSD(T)
and DFT methods. The two most stable doublet structures, the C2v planar
including the two Hs bound terminally and C1 non-planar showing one H
in terminal site and the other in threefold site are found to be essentially
degenerate. Although the reaction of Al3 with H2 to yield
Al3H2 is found to be significantly exothermic, by 23.5 kcal/mol,
this hydrogenation is impeded by a considerable kinetic barrier of 16 kcal/mol. Our result is consistent with the observed
lack of reactivity of
Aln towards H2(D2) for n=3 under thermal conditions [3].
The quartet Al3H2 isomers are predicted to lie 16–21 kcal/mol higher
in energy than the doublet analogues. Further dimerization of
Al3H2 to form Al6H4 has also been examined.
Electronic supplementary material Supplementary Online Material 相似文献
20.
X. Liang Y.-H. Luo X.-J. Feng T. T. Cao L. X. Zhao 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):93-101
The structures, binding energies, and electronic properties of
Cn and NaCn (n=2–12) clusters have been systematically
investigated using density functional theory (DFT). A number of
previously undiscovered isomers of NaCn clusters are reported,
including fan-like, linear and three-dimensional structures.
Moreover, NaCn clusters with even n are found to be more
stable than those with odd n, in contrast with
the case of Cn clusters. 相似文献