共查询到20条相似文献,搜索用时 15 毫秒
1.
V. L. Gilyarov A. I. Slutsker V. P. Volodin A. I. Laius 《Physics of the Solid State》1998,40(8):1404-1406
The dependence of the temperature on the external adiabatic deformation is determined for a one-dimensional model of a solid
— chains of atoms with an anharmonic interaction. The resulting dependences of the average kinetic and potential components
of the internal energy on this deformation are compared with a model of adiabatic loading of a single oscillator.
Fiz. Tverd. Tela (St. Petersburg) 40, 1548–1551 (August 1998) 相似文献
2.
B. A. Strukov E. P. Ragula S. V. Arkhangel’skaya I. V. Shnaidshtein 《Physics of the Solid State》1998,40(1):94-95
Using precise vacuum adiabatic calorimetry it is shown that the specific heat of the model ferroelectric crystal TGS does
not exhibit the logarithmic singularity predicted by theory above the transition temperature. This discrepancy with the available
specific heat data in the literature, obtained by dynamical measurements, is discussed with allowance for the maximum attainable
measurement accuracy (0.3%) in the static adiabatic experiment.
Fiz. Tverd. Tela (St. Petersburg) 40, 106–108 (January 1998) 相似文献
3.
V.A. Pashchenko A. Sulpice F. Mila P. Millet A. Stepanov P. Wyder 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,21(4):473-476
We report on the magnetic susceptibility and electron spin resonance measurements on polycrystalline samples of the vanadium
oxide VOSb2O4, a quasi-one-dimensional S
= 1/2 Heisenberg system. The susceptibility vanishes at zero temperature, but there is no cusp at the onset of the susceptibility
drop, and the ESR linewidth exhibits an increase characteristic of a phase transition at a much lower temperature. We show
that this behaviour is consistent with the formation of a pseudo-gap in a spin-Peierls system in the adiabatic limit.
Received 7 February 2001 and Received in final form 24 April 2001 相似文献
4.
M. Monnerville J.M. Robbe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,5(3):381-387
The optical potential discrete variable representation method (OP-DVR) has been applied recently to calculate resonances in
the framework of the diabatic representation [J. Chem. Phys. 101, 7580 (1994)]. This method is based on the conjoint use of the discrete variable representation (DVR) method and the properties
of a complex absorbing potential (CAP). The OP-DVR method is the DVR version of the CAP stabilization method initially proposed
by Jolicard and Austin [Chem. Phys. Lett. 121, 106 (1985)]. In the present study, we show that this efficient and accurate method can also be applied within the adiabatic
representation since it allows one to overcome in a simple way, numerical difficulties associated with the first derivative
operator which appears in the expression of non adiabatic couplings. Within the OP-DVR method, the choice of the representation
(diabatic or adiabatic) is governed by physical arguments and by the fact that the potentials and the couplings are known
in one or the other of these two representations. In the case where the potentials and the couplings are obtained in the adiabatic
representation, we show in this paper that the transformation into the diabatic framework is not necessary. We demonstrate
that the discrete variable representation can be a simple and an efficient way to deal with the adiabatic representation.
Received: 30 April 1998 / Revised: 29 September 1998 /Accepted: 21 October 1998 相似文献
5.
The Raman interaction of optical fields with a Bose condensate is studied in the adiabatic regime. A superposition of operators
is found — one annihilating an atom in a metastable state and the other annihilating a photon in resonance with a transition
from the ground state to an excited state — which is an adiabatic invariant of the problem (Raman polariton). Possible applications
for Bose-condensate diagnostics and development of atomic lasers are proposed.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 7, 473–477 (10 October 1996) 相似文献
6.
A. U. Sheleg T. I. Dekola N. P. Tekhanovich A. M. Luginets 《Physics of the Solid State》1997,39(4):545-546
The specific heat of LiB3O5 crystals is measured by adiabatic calorimetry. The experimental data on the specific heat are used to calculate the change
in the thermodynamic functions (the entropy, enthalpy, and Gibbs free energy) and the Debye temperature ΘD(T) of crystalline LiB3O5.
Fiz. Tverd. Tela (St. Petersburg) 39, 624–625 (April 1997) 相似文献
7.
In the tight-binding random Hamiltonian on Z
d
, we consider the charge transport induced by an electric potential which varies sufficiently slowly in time, and prove that it is almost surely equal to zero at high disorder. In order to compute the charge transport, we adopt the adiabatic approximation and prove a weak form of adiabatic theorem while there is no spectral gap at the Fermi energy. 相似文献
8.
G.Q. Li P. Peng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,64(1):79-84
We investigate the conversion of ultracold bosonic atoms to heteronuclear tetramer
A3B by an Efimov resonance-assisted stimulated Raman adiabatic passage
scheme. In view of recent experiments involving heteronuclear Efimov trimers KKRb and
KRbRb [Phys. Rev. Lett. 103, 043201 (2009)], the intermediate state populated
by heteronuclear trimer A2B in the conversion process is considered. The
atom-molecule dark state solution for a system with a population imbalance is derived
analytically, and the role played by the imbalance in the conversion is studied. In
addition, the effects of the external field parameters (including photoassociated pulse
intensity, width, magnetic coupling strength and its detuning) on the conversion are
discussed via the concept of adiabatic fidelity. 相似文献
9.
Two-dimensional and three-dimensional bipolarons of large radius, symmetrized with respect to the coordinate parts of the
two-center wave functions, are investigated in the adiabatic approximation with allowance for dynamic interelectronic correlations.
The adiabatic potential lines are plotted. It is shown that the quasimolecular configuration appearing in the Hartree-Fock
approximation is unstable in both the two-dimensional and the three-dimensional cases. The ground state is a one-center configuration.
Estimates are given for the binding energy and the heat of dissociation of a bipolaron.
Fiz. Tverd. Tela (St. Petersburg) 39, 441–443 (March 1997) 相似文献
10.
We continue to analyse the known law of adiabatic transformation for an ideal gas PV5/3 = Constant, where P is the pressure and V is the volume, and following the approach of non-relativistic quantum mechanics which we suggested in a previous work (Yarman et al. 2010 Int. J. Phys. Sci. 5 1524). We explicitly determine the constant for the general parallelepiped geometry of a container. We also disclose how the quantum numbers associated with molecules of an ideal gas vary through an arbitrary adiabatic transformation. Physical implications of the results obtained are discussed. 相似文献
11.
ABSTRACTThe adiabatic potential energy curves for ground and many excited states of 1, 3Σ+, 1,3Π, 1,3Δ symmetries of the LiNa molecule have been performed. We have used an ab initio approach based on non-empirical pseudopotentials, parameterised l-dependent polarisation potentials and full configuration interaction calculations. In addition, the adiabatic potential energy curves determined in our previous work [Mabrouk and Berriche, J. Phys. B: At. Mol. Opt. Phys. 41, 155101 (2008).] are corrected by using a diabatisation procedure, based on the effective Hamiltonian theory and an effective metric. The diabatic permanent moments for first 10 1Σ+ electronic states show linear behaviours, especially at intermediate and large distance. The transition dipole moment between neighbour states has revealed many peaks located around the avoided crossing positions. The radial coupling between the adiabatic states was calculated using the Hellmann-Feynman formula and numerical differentiation of the rotation matrix. The first and the second derivatives revealed many peaks, associated to neutral-neutral and ionic-neutral crossings. Furthermore, the radial coupling is used to evaluate the adiabatic correction, which is found to be of an order of tens and hundreds of cm?1, especially of higher excited states. In addition, we have determined the vibrational level spacing for all studied states. 相似文献
12.
C.P. Sun D.L. Zhou S.X. Yu X.F. Liu 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,13(1):145-155
Based on the Born-Oppenhemer approximation, the concept of adiabatic quantum entanglement is introduced to account for quantum
decoherence of a quantum system due to its interaction with a large system of one or a few degrees of freedom. In the adiabatic
limit, it is shown that the wave function of the total system formed by the quantum system plus the large system can be factorized
as an entangled state with correlation between adiabatic quantum states and quasi-classical motion configurations of the large
system. In association with a novel viewpoint about quantum measurement, which has been directly verified by most recent experiments
[e.g., S. Durr et al., Nature 33, 359 (1998)], it is shown that the adiabatic entanglement is indeed responsible for the quantum decoherence and thus can
be regarded as a “clean” quantum measurement when the large system behaves as a classical object. By taking the large system
respectively to be a macroscopically distinguishable spatial variable, a high spin system and a harmonic oscillator with a
coherent initial state, three illustrations are presented with their explicit solutions in this paper.
Received 26 February 2000 and Received in final form 14 July 2000 相似文献
13.
A. P. Zhernov 《Physics of the Solid State》1998,40(3):377-382
The electronic specific heat of metals with quantum defects in the superconducting state is examined. The role of the electron-polaron
effect, as well as that of the level population factor of two-level states, is analyzed in an adiabatic approach. The cases
of intermediate and strong coupling are discussed.
Fiz. Tverd. Tela (St. Petersburg) 40, 413–418 (March 1998) 相似文献
14.
L. E. Golub 《Physics of the Solid State》1997,39(10):1673-1676
Exciton localization at islands of cylindrical shape in quantum-well structures has been studied theoretically. It is shown
that an exciton localizes at such islands, as a rule, as a whole. The validity regions of the adiabatic approximation in factorization
of the exciton wave function have been established. The variation in the character of localization with increasing quantum-well
barrier height is analyzed.
Fiz. Tverd. Tela (St. Petersburg) 39, 1871–1874 (October 1997) 相似文献
15.
Jinglei Li Xiaobo Zhao Tian Zhang Xiaoshi Qian Ying Hou Lu Yang 《Phase Transitions》2017,90(1):99-103
ABSTRACTRelaxor ferroelectric polymer poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF-TrFE-CFE)) and its blends have been shown to exhibit a giant electrocaloric effect (ECE) over a broad temperature range, e.g. from 0 to 50 °C. Here, a special calorimeter was designed to directly characterize the heat absorbed QECE due to ECE cooling of the blend of P(VDF-TrFE-CFE) with P(VDF-TrFE) 65/35 mol% copolymer down to ?15 °C, which covers the temperature range for many refrigeration applications. From QECE, the isothermal entropy change ΔS and adiabatic temperature change ΔT are deduced. The data reveal that at ?15 °C the relaxor terpolymer/copolymer blend generates ΔS = 23.0J kg?1 K?1 and ΔT = 5.1K under 100 MV/m, which are still more than 65% of the ECE at room temperature. This temperature is far below the dielectric peak temperature of the relaxor blend and the results reveal the promise of the relaxor polymers for a broad range of EC cooling applications. 相似文献
16.
Recently, Zhang and Lu provided a quantum search algorithm based on partial adiabatic evolution, which beats the time bound of local adiabatic search when the number of marked items in the unsorted database is larger than one. Later, they found that the above two adiabatic search algorithms had the same time complexity when there is only one marked item in the database. In the present paper, following the idea of Roland and Cerf [Roland J and Cerf N J 2002 Phys. Rev. A 65 042308], if within the small symmetric evolution interval defined by Zhang et al., a local adiabatic evolution is performed instead of the original “global” one, this “new” algorithm exhibits slightly better performance, although they are progressively equivalent with M increasing. In addition, the proof of the optimality for this partial evolution based local adiabatic search when M=1 is also presented. Two other special cases of the adiabatic algorithm obtained by appropriately tuning the evolution interval of partial adiabatic evolution based quantum search, which are found to have the same phenomenon above, are also discussed. 相似文献
17.
V.S. Gerdjikov 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,29(2):237-241
We compare the Hamiltonian properties of the N-soliton solutions of the NLSE in the adiabatic approximation and show how it matches the Hamiltonian formulation for the
complex Toda chain which describes the adiabatic N-soliton interactions.
Received 21 October 2001 Published online 2 October 2002
RID="a"
ID="a"e-mail: gerjikov@inrne.bas.bg 相似文献
18.
J.-P. Pouget 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,20(3):321-333
CuGeO3 exhibits a Spin-Peierls (SP) transition, at T
SP
= 14.3 K, which is announced above 19 K by an important regime of one-dimensional (1D) pretransitional lattice fluctuations which
can be detected until about 40 K using X-ray diffuse scattering investigations. A quantitative analysis of this scattering
shows that in this 1D direction the correlation length follows the “universal” behaviour expected for the thermal fluctuations
of a real order parameter which characterizes the lattice dimerization. This allows to define a 1D mean-field temperature,
T
SP
MF
, of about 60 K and invalidates any mean field scenario for the SP transition of CuGeO3. As T
SP
MF
is as high as 4
T
SP
we propose that the 3D-SP order is achieved by the interchain coupling between 1D solitons which form below about 16-20 K.
CuGeO3 being in the non-adiabatic regime, it is also suggested that the observed pretransitional fluctuations of CuGeO3 originate from the X-ray scattering on a very broad damped critical response of lower frequency than the “critical” phonon
modes. From the quantitative analysis of the 1D fluctuations we also estimate the microscopic parameters of the SP chain.
These parameters allow to locate CuGeO3 close to the quantum critical boundary separating the gapped SP ground state to the ungapped anti-ferromagnetic ground state.
The vicinity of a quantum critical point emphasizes the role of the quantum and non-adiabatic fluctuations and the importance
of the interchain coupling in the physics of CuGeO3. Finally we compare these findings with those obtained for the organic SP systems (BCPTTF)2PF6, (TMTTF)2PF6 and MEM(TCNQ)2. From a similar analysis of the pretransitional lattice fluctuations it is found that (BCPTTF)2PF6 and (TMTTF)2PF6 are located on the SP gapped classical-quantum boundary and are in the adiabatic regime where the fluctuations lead to the
formation of a pseudo-gap in the spin degrees of freedom. Differently, we place MEM(TCNQ)2 inside the SP quantum phase around the crossover line between the adiabatic and non-adiabatic regimes.
Received 13 September 2000 and Received in final form 6 February 2001 相似文献
19.
Heat capacity of Rb2ZnBr4 as a function of γ irradiation dose has been measured within the 85–300 K range by the adiabatic calorimeter technique. It is shown that, as
the irradiation dose increases, the heat capacity peak in the vicinity of the incommensurate-commensurate first-order phase
transition (PT) decreases, and the transition temperature T
c
increases. The heat capacity peak in the region of the second-order PT at T
3=112 K does not depend on γ irradiation, both in magnitude and in position, just as the heat capacity throughout the remainder of the temperature range
studied.
Fiz. Tverd. Tela (St. Petersburg) 40, 1106–1108 (June 1998) 相似文献
20.
在磁性体磁化过程中, 决定其能够达到的最高温度, 对磁热材料的优化选取是重要的. 本文以钆镓石榴石(Gd3Ga5O12) 为例, 根据高磁场下趋近饱和定律的思想, 给出了低温、超强磁场下, Gd3Ga5O12晶体等效磁化率的定量形式. 在外磁场从0---40 T范围内, 计算了该晶体的磁熵变、声子熵变以及磁性体温度随外磁场的变化, 结果均与实验值符合较好. 利用声子熵变与饱和磁熵变曲线交点的唯一性, 给出了在磁性体磁化过程中, 确定其温度达到最大值的方法, 预言了Gd3Ga5O12晶体在绝热磁化过程中达到的最高温度为64.7K. 该方法还可以对所加外磁场大小进行预言或估计. 相似文献