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1.
R. Rai 《Zeitschrift für Physik B Condensed Matter》1995,99(1):327-332
The closeness of low-lying T1u and T1g levels of C
60
−
could enable their mixing under an odd parity vibration of (T1 u + T1 g ⊗ (hg + τ1 u)type. In addition, the two levels are susceptible to Jahn-Teller interaction due to five-fold degenerate hg vibrations. This complex problem of (T1u+T1g)⊗(hg+τ1u) vibronic interaction is transformed to a form similar to T2g ⊗ (εg + τ2g) vibronic problem of octahedral symmetry. The problem is analysed in an infinite coupling model and compared with the experimental
spectroscopic results for the C
60
−
radical. The resulting parameters are used to calculate the pair-binding energy and superconducting transition temperature
in C
60
n−
fullerides. Vibronic mixing with the T1g level is found to be responsible for maximising the pair-binding energy at the doping level n=3. It is also found to be an
important source of Tc enhancement. 相似文献
2.
F. Michelot M. Rey 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2005,33(3):357-386
Several problems in vibronic spectroscopy are solved
within the effective Hamiltonian formalism combined with Lie
algebraic methods. We consider mainly vibronic interactions in
orbital doublets for molecules with a principal symmetry axis of
order n=4k (or n even for Dnd symmetry groups). Effective
Hamiltonian models for E ⊗(b1+b2), E ⊗
(bi+aj) and E ⊗(bi+ e) Jahn-Teller dynamical systems
are discussed as well as some correlations with previous studies
established. 相似文献
3.
C. S. Yu X. X. Yi H. S. Song 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,49(2):273-278
For a tripartite pure state superposed by two individual states, the bipartitely shared entanglement can always be achieved
by local measurements of the third party. Consider the different aims of the third party, i.e. maximizing or minimizing the
bipartitely shared entanglement, we find bounds on both the possible bipartitely shared entanglement of the superposition
state in terms of the corresponding entanglement of the two states being superposed. In particular, by choosing the concurrence
as bipartite entanglement measure, we obtain calculable bounds for tripartite (2 ⊗ 2 ⊗ n)-dimensional cases. 相似文献
4.
E. Nir Ch. Plützer K. Kleinermanns M. de Vries 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,20(3):317-329
The vibronic spectra of laser desorbed and jet cooled guanine (G) adenine (A), and cytosine (C) consist of bands from four,
two and two major tautomers respectively, as revealed by UV-UV and IR-UV double resonance spectroscopy. The vibronic spectrum
of adenine around 277 nm consists of weak nπ* and strong ππ* transitions, based on IR-UV and deuteration experiments. Precise ionization potentials of G and A were determined with 2-color,
2-photon ionization. We also measured vibronic and IR spectra of several base pairs. GC exhibits a HNH ... OH/NH ... N/C=O ... HNH bonding similar to the Watson-Crick GC base pair but with C as enol tautomer. One GG isomer exhibits non-symmetric hydrogen
bonding with HNH ... N/NH ... N/C=O ... HNH interactions. A second observed GG isomer has a symmetrical hydrogen bond arrangement with C=O ... NH/NH ... O=C bonding. Two CC isomers were observed with symmetrical C=O ... NH/NH ... O=C bonding and nonsymmetrical C=O ... HNH/NH ... N interaction, respectively. Guanosine (Gs), 2-DeoxyGs und 3-DeoxyGs each exhibit only one isomer in the investigated wavelength
range around 290 nm with a strong intramolecular sugar(5-OH) ... enolguanine(3-N) hydrogen bond.
Received 16 June 2002 / Received in final form 15 July 2002 Published online 13 September 2002 相似文献
5.
Many recent experiments have established that the Jahn-Teller (JT) effect plays a very important role in determining the properties of the C60 molecule. A review of the underlying theory developed by the Nottingham group is presented for cases in which distinct minima in the potential energy surface occur. This relates directly to the C60 molecule through the consideration of the T ⊗ h and H ⊗ h JT systems. When only linear coupling terms exist in the T ⊗ h system, the minima form a continuous trough of SO(3) symmetry and new methods must be used. Some details of these results are presented. 相似文献
6.
7.
A. O. Sorokin A. V. Syromyatnikov 《Journal of Experimental and Theoretical Physics》2011,113(4):673-677
Two models of classic XY antiferromagnets in three dimensions are studied by Monte Carlo simulation: the model on a simple
cubic lattice with two extra intralayer exchanges and the model on a stackedtriangular lattice with an extra interlayer exchange.
In suggested models, the order parameters are magnetization and two chiral parameters. A transition corresponds to breaking
ℤ2 ⊗ ℤ2 ⊗ SO(2) symmetry. A distinct first order transition is found in both models. 相似文献
8.
In verifying and validating models of nonlinear processes it is important to incorporate information from observations in an efficient manner. Using the idea of synchronization of nonlinear dynamical systems, we present a framework for connecting a data signal with a model in a way that minimizes the required coupling yet allows the estimation of unknown parameters in the model. The need to evaluate unknown parameters in models of nonlinear physical, biophysical, and engineering systems occurs throughout the development of phenomenological or reduced models of dynamics. Our approach builds on existing work that uses synchronization as a tool for parameter estimation. We address some of the critical issues in that work and provide a practical framework for finding an accurate solution. In particular, we show the equivalence of this problem to that of tracking within an optimal control framework. This equivalence allows the application of powerful numerical methods that provide robust practical tools for model development and validation. 相似文献
9.
J.S. Gibb G. Hancock A. Hutchinson R. Peverall G.A.D. Ritchie 《Applied physics. B, Lasers and optics》2003,76(1):97-105
A simple technique is demonstrated for the accurate determination of pressure-induced line shifts of water in air. High- and
low-pressure water samples are simultaneously probed on selected overtone transitions at 1.32 μm using a current-modulated
distributed-feedback diode laser and harmonic detection. The resultant profiles yield an average line shift of -293±30 MHz/atm
for the 3,3,0 (002)2,2,1 (000)transition at 227251 GHz and -134±7 MHz/atm for the 3,2,1 (002)2,1,2 (000) transition at 227027 GHz.
Comparisons are made between first- and second-harmonic detection, and wavelength- and frequency-modulation regimes. The effect
of modulation broadening on the returned line shifts is quantified.
Received: 12 August 2002 / Revised version: 21 October 2002 / Published online: 8 January 2003
RID="*"
ID="*"Corresponding author. Fax: +44-01865/275410, E-mail: gus.hancock@chemistry.ox.ac.uk 相似文献
10.
Francesco Cianfrani Giovanni Montani 《International Journal of Theoretical Physics》2007,46(3):471-485
In this work, we develop a geometrical unification theory for gravity and the electro-weak model in a Kaluza-Klein approach;
in particular, from the curvature dimensional reduction Einstein–Yang–Mills action is obtained. We consider two possible space-time
manifolds: 1) V
4⊗ S
1⊗ S
2 where isospin doublets are identified with spinors; 2) V
4⊗ S
1⊗ S
3 in which both quarks and leptons doublets can be recast into the same spinor, such that the equal number of quark generations
and leptonic families is explained.
Finally a self-interacting complex scalar field is introduced to reproduce the spontaneous symmetry breaking mechanism; in
this respect, at the end, we get an Higgs fields whose two components have got opposite hypercharges. 相似文献
11.
We show that two appropriate realizations of the su(4) algebra allow the construction of all electronic operators needed for the study of vibronic and rovibronic interactions in a G′ electronic state. In each case a full bosonic realization is made and all matrix elements are calculated. Illustrations of our formalism and comparisons with previous approaches are made in the case of ν5(F2g) and ν3(F1u) modes. 相似文献
12.
Y. H. Zhang T. Hayakawa M. Oshima Y. Toh J. Katakura Y. Hatsukawa M. Matsuda N. Shinohara T. Ishii H. Kusakari M. Sugawara T. Komatsubara 《The European Physical Journal A - Hadrons and Nuclei》2000,8(4):439-442
High spin states in 178Ir have been studied via the 152Sm(31P, 5nγ)178Ir reaction through excitation functions, X-γ and γ-γ-t coincidence measurements. According to the band structure characteristics
and the measured intraband B(M1)/B(E2) ratios, two rotational bands are identified and assigned to be associated with the πh
9/2⊗νi
13/2 and πh
11/2⊗νi
13/2 configurations, respectively. Both bands show the signature inversion feature.
Received: 23 March 2000 / Accepted: 31 July 2000 相似文献
13.
J. Pollmann R. Kalla P. Krüger A. Mazur G. Wolfgarten 《Applied Physics A: Materials Science & Processing》1986,41(1):21-38
A brief review on recent progress in the theory of electronic, structural, and vibronic properties of semiconductor surfaces is presented with particular emphasis on the empirical and selfconsistent scattering theoretical method for semiinfinite systems. The current knowledge of the Si(001) (2×1) surface is discussed in detail. The Ge(001) (2×1) surface, as well as, the clean and the Ge-covered GaAs(110) surfaces are addressed, in addition. In the discussion of the results it is shown, that the scattering theoretical method is an extremely versatile tool for calculating electronic surface properties unambiguously with high spectral resolution concerning energy, wavevector, layer-index and orbital type. Currently used approaches for calculating the total energy, Hellmann-Feynman forces and optimal structure models are summarized. Using the total energy as a starting point, the calculation of atomic force constants and surface phonon spectra is exemplified. 相似文献
14.
Previously, we have proposed a direct simulation scheme for colloidal dispersions in a Newtonian solvent (Phys. Rev. E 71, 036707 (2005)). An improved formulation called the “Smoothed Profile (SP) method” is presented here in which simultaneous
time-marching is used for the host fluid and colloids. The SP method is a direct numerical simulation of particulate flows
and provides a coupling scheme between the continuum fluid dynamics and rigid-body dynamics through utilization of a smoothed
profile for the colloidal particles. Moreover, the improved formulation includes an extension to incorporate multi-component
fluids, allowing systems such as charged colloids in electrolyte solutions to be studied. The dynamics of the colloidal dispersions
are solved with the same computational cost as required for solving non-particulate flows. Numerical results which assess
the hydrodynamic interactions of colloidal dispersions are presented to validate the SP method. The SP method is not restricted
to particular constitutive models of the host fluids and can hence be applied to colloidal dispersions in complex fluids. 相似文献
15.
M. A. Jafarizadeh N. Behzadi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):729-744
In this work, new types of EWs are introduced. They are
constructed by using real skew-symmetric operators defined on a single
party subsystem of a bipartite d⊗d system and a maximal
entangled state in that system. A canonical form for these
witnesses is proposed which is called canonical EW in corresponding to canonical real skew-symmetric operator. Also for each
possible
partition of the canonical real skew-symmetric operator
corresponding EW is obtained. The method used for
d⊗d case is extended to d1⊗d2 systems.
It is shown that there exist Cd2
d1 distinct
possibilities to construct EWs for a given d1⊗
d2 Hilbert space. The optimality and nd-optimality problem is
studied for each type of EWs. In each step, a large
class of quantum PPT states is introduced. It is shown that among
them there exist entangled PPT states which are
detected by the constructed witnesses. Also the idea of canonical EWs is extended to obtain other EWs with greater PPT entanglement
detection power. 相似文献
16.
G.W. Baxter M.A. Payne B.D.W. Austin C.A. Halloway J.G. Haub Y. He A.P. Milce J.F. Nibler B.J. Orr 《Applied physics. B, Lasers and optics》2000,71(5):651-663
Optical parametric oscillator (OPO) and amplifier (OPA) devices are useful for spectroscopic sensing of chemical processes
in laboratory, industrial, and environmental settings. This is particularly true of nanosecond-pulsed, continuously tunable
OPO/OPA systems, for which we survey a variety of instrumental strategies, together with actual spectroscopic measurements.
The relative merits of OPO wavelength control by intracavity gratings and by injection seeding are considered. A major innovation
comprises an OPO with a ring cavity based on periodically poled lithium niobate (PPLN) and injection-seeded by a single-mode
tunable diode laser (TDL). Active cavity control by an ‘intensity dip’ method yields an optical bandwidth ≤0.005 cm-1 (150 MHz), which compares favourably with the performance of advanced grating-tuned OPO/OPA systems. A novel adaptation of
this TDL-seeded PPLN OPO employs a compact, inexpensive multimode pump laser, with which it is still possible to obtain continuously
tunable single-mode signal output. Cavity ringdown (CRD) spectroscopy also figures prominently, with infrared (IR) CRD spectra
from both grating-scanned and TDL-seeded OPOs reported. Finally, a tunable ultraviolet (UV) source, combining a TDL-seeded
passive-cavity OPO and a sum-frequency generation stage, is developed for measurements of time-resolved IR-UV double resonance
spectra of acetylene and UV laser-induced fluorescence spectra of nitric oxide.
Received: 28 March 2000 / Published online: 13 September 2000 相似文献
17.
M. A. Jafarizadeh N. Behzadi Y. Akbari 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(1):197-203
On the basis of linear programming, new sets of entanglement witnesses (EWs) for 3⊗3 and 4⊗4 systems are constructed. In both
cases, the constructed EWs correspond to the hyper-planes contacting, without intersecting, the related feasible regions at
line segments and restricted planes respectively. Due to the special property of the contacting area between the hyper-planes
and the feasible regions, the corresponding hyper-planes can be turned around the contacting area throughout a bounded interval
and hence create an infinite number of EWs. As these EWs are able to detect entanglement of some PPT states, they are non-decomposable
(nd-EWs). 相似文献
18.
Lichang Yin Yunzuo Liu Jingbin Lu Guangyi Zhao Xianfeng Li Xiaoguang Wu Guangsheng Li Shuxian Wen Chunxiang Yang 《The European Physical Journal A - Hadrons and Nuclei》2001,11(4):379-383
High-spin states of 160Lu have been studied through the 144Sm( 19F, 3n) reaction. The previously known πh
11/2⊗υi
13/2 yrast band is extended from I
π = 21- to 25- and a four quasiparticle band with configuration πh
11/2[523]7/2 -⊗υh
9/2[521]3/2 -⊗ (υi
13/2)2 is reported.
Received: 21 May 2001 / Accepted: 19 July 2001 相似文献
19.
N. Hashimoto T.R. Saitoh G. Sletten R.A. Bark M. Bergström K. Furuno T. Komatsubara T. Shizuma S. Törmänen P.G. Varmette 《The European Physical Journal A - Hadrons and Nuclei》1998,2(4):327-330
Abstact: High-spin states in 183Re have been studied using the 176Yb(11B,4n) reaction at 52 and 57 MeV. Two high-K bands have been observed directly by a time-correlated γ-γ coincidence measurement. One of the bands is built on an isomeric
K
π=(25/2)+ state at E
x= 1908 keV with a half-life of 0.82(2) ms. The other band, assigned as K
π=(29/2)− at E
x= 2739 keV, decays to the (25/2)+ band. These bands are interpreted as three-quasiparticle structures, π(5/2)+[402] &⊗ν(9/2)+[624] ⊗ν(11/2)+[615] for the (25/2)+ band and π(9/2)−[514] ⊗ν(9/2)+[624] ⊗ν(11/2)+[615] for the (29/2)− band. The K
π= (29/2)− band becomes strongly Coriolis mixed with increasing spin and is gradually changing into a low-K s-band structure.
Received: 20 April 1998 相似文献
20.
W. Meier O. Keck B. Noll O. Kunz W. Stricker 《Applied physics. B, Lasers and optics》2000,71(5):725-731
A standard burner for confined swirling natural gas flames is presented which was developed within the German TECFLAM cooperation.
The aims of the TECFLAM research program are the establishment of an extensive experimental database from selective flames
and the validation and improvement of mathematical combustion models. In this paper, results from joint PDF measurements of
temperature, mixture fraction, and major species concentrations in a turbulent diffusion flame with 150 kW thermal load, equivalence
ratio 0.833, and swirl number 0.9 are presented. Major aspects of the investigation are the general quantitative characterization
of the flame and the study of the thermochemical state, e.g. effects of turbulence–chemistry interactions. Scatterplots of
temperature, CH4, and CO mole fractions as well as mean mixture fraction and temperature fields are presented and discussed. Furthermore,
CFD calculations have been performed using the code Fluent 5 as an example of a commercially available code that is frequently
used for technical applications. The comparison between the calculated and measured results reveals some significant deviations
which are discussed with respect to the applicability of this code to swirling turbulent flames.
Received: 19 April 2000 / Revised version: 15 June 2000 / Published online: 5 October 2000 相似文献