共查询到20条相似文献,搜索用时 125 毫秒
1.
The probability representation for quantum states of the universe in which the states are described by a fair probability
distribution instead of wave function (or density matrix) is developed to consider cosmological dynamics. The evolution of
the universe state is described by standard positive transition probability (tomographic transition probability) instead of
the complex transition probability amplitude (Feynman path integral) of the standard approach. The latter one is expressed
in terms of the tomographic transition probability. Examples of minisuperspaces in the framework of the suggested approach
are presented. Possibility of observational applications of the universe tomographs are discussed. 相似文献
2.
K.-Y. LEEA.A. RENSHAW 《Journal of sound and vibration》2002,258(4):725-739
The spectral collocation method is used to determine the stability of parametrically excited systems and compared with the traditional transition matrix approach. Results from a series of test problems demonstrate that spectral collocation converges rapidly. In addition, the spectral collocation method preserves the sparsity of the underlying system matrices, a property not shared by the transition matrix approach. As a result, spectral collocation can be used for very large systems and can utilize sparse eigensolvers to reduce computational memory and time. For the large-scale system studied (up to 40 degrees of freedom), the spectral collocation method was on average an order of magnitude faster than the transition matrix approach using Matlab. This computational advantage is implementation specific; in a C implementation of the algorithm, the transition matrix method is faster than the spectral collocation. Overall, the method proves to be simple, efficient, reliable, and generally competitive with the transition matrix method. 相似文献
3.
从价核子自由度出发构造出核跃迁电荷/电流密度算符,采用Dyson玻色子展开技术给出了获取核玻色子形式跃迁电荷/电流密度有效算符的一种微观方法(BE方法).利用微观相互作用玻色子模型(IBM)提供的波函数可在玻色子态空间中求出核跃迁电荷/电流密度,结合电子-核散射以及核电磁跃迁的形式理论,建立了可研究电子-核散射各种形状因子,微分散射截面以及核约化跃迁几率、电磁多极矩、核态g因子等物理量的理论方案.在一种微观sdIBM-2框架下,结合现有理论方案,初步计算了 相似文献
4.
Y. Kafri D. Mukamel L. Peliti 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(1):135-146
Existing experimental studies of the thermal denaturation of DNA yield sharp steps in the melting curve suggesting that the
melting transition is first order. This transition has been theoretically studied since the early sixties, mostly within an
approach in which the microscopic configurations of a DNA molecule consist of an alternating sequence of non-interacting bound
segments and denaturated loops. Studies of these models neglect the repulsive, self-avoiding, interaction between different
loops and segments and have invariably yielded continuous denaturation transitions. In the present study we take into account
in an approximate way the excluded-volume interaction between denaturated loops and the rest of the chain. This is done by
exploiting recent results on scaling properties of polymer networks of arbitrary topology. We also ignore the heterogeneity
of the polymer. We obtain a first-order melting transition in d = 2 dimensions and above, consistent with the experimental results. We also consider within our approach the unzipping transition,
which takes place when the two DNA strands are pulled apart by an external force acting on one end. We find that the under
equilibrium condition the unzipping transition is also first order. Although the denaturation and unzipping transitions are
thermodynamically first order, they do exhibit critical fluctuations in some of their properties. For instance, the loop size
distribution decays algebraically at the transition and the length of the denaturated end segment diverges as the transition
is approached. We evaluate these critical properties within our approach.
Received 21 August 2001 and Received in final form 26 January 2002 相似文献
5.
A. Coniglio J.J. Arenzon A. Fierro M. Sellitto 《The European physical journal. Special topics》2014,223(11):2297-2306
A long standing problem in glassy dynamics is the geometrical interpretation of clusters and the role they play in the observed scaling laws. In this context, the mode-coupling theory (MCT) of type-A transition and the sol–gel transition are both characterized by a structural arrest to a disordered state in which the long-time limit of the correlator continuously approaches zero at the transition point. In this paper, we describe a cluster approach to the sol-gel transition and explore its predictions, including universal scaling laws and a new stretched relaxation regime close to criticality. We show that while MCT consistently describes gelation at mean-field level, the percolation approach elucidates the geometrical character underlying MCT scaling laws. 相似文献
6.
We have investigated the pressure-induced phase transition of NiO and other structural properties using three-body potential
approach. NiO undergoes phase transition from B1 (rocksalt) to B2 (CsCl) structure associated with a sudden collapse in volume
showing first-order phase transition. A theoretical study of high pressure phase transition and elastic behaviour in transition
metal compounds using a three-body potential caused by the electron shell deformation of the overlapping ion was carried out.
The phase transition pressure and other properties predicted by our model is closer to the phase transition pressure predicted
by Eto et al.
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9.
Phase transition and critical properties of Ising-like spin-orbital interacting systems in 2-dimensional triangular lattice are investigated. We first show that the ground state of the system is a composite spin-orbital ferro-ordered phase. Though Landau effective field theory predicts the second-order phase transition of the composite spin-orbital order, however, the critical exponents obtained by the renormalization group approach demonstrate that the spin-orbital order-disorder transition is far from the second-order, rather, it is more close to the first-order. The unusual critical behavior near the transition point is attributed to the fractionalization of the composite order parameter. 相似文献
10.
The critical exponent b of lattice gauge theory in (3 + 1)-dimension is calculated by using approximate analytical results of (L) in the deconfining phase transition region. The obtained b = 0.3622 ± 0.0027 confirms the universality conjecture. An extrapolating approach to determine the deconfining phase transition point is proposed. 相似文献
11.
A quantum phase transition in strongly correlated Fermi systems beyond the topological quantum critical point has been studied
using the Fermi liquid approach. The transition takes place between topologically equivalent states with three Fermi surface
sheets, but one of them is characterized by a quasiparticle halo in the quasiparticle momentum distribution n(p), and the other one is characterized by a hole pocket. It has been found that the transition between these states is a first-order
phase transition for the interaction constant g and temperature T. The phase diagram in the vicinity of this transition has been constructed. 相似文献
12.
We study one-dimensional disordered bosons at large commensurate filling. Using a real space renormalization group approach, we find a new random fixed point which controls a phase transition from a superfluid to an incompressible Mott glass. The transition can be tuned by changing the disorder distribution even with vanishing interactions. We derive the properties of the transition, which suggest that it is in the Kosterlitz-Thouless universality class. 相似文献
13.
An approach based on the Ising model has been proposed for describing a ferroelectric phase transition in a system of interacting
identical small particles. It has been found that the shift of the phase transition temperature with respect to the transition
point in a bulk sample is affected by both the size effects due to the smallness of the particles and their interaction with
each other. The behavior of the dependence of the phase transition temperature on the distance between particles is determined
by the nature of the interparticle interaction. An analysis has demonstrated that the interaction between small particles
should be taken into account in the interpretation of the ferroelectric properties of nanocomposite materials. 相似文献
14.
The liquid-vapor phase transition in hot nuclear matter is investigated in a field-theoretical approach employing euclidean-space (imaginary time) path-integral techniques. This approach allows us to study the nucleation due to both quantum and thermodynamic fluctuations. The bubbles of the new phase appear as instanton solutions of the euclidean-space field equations. The critical bubble sizes and associated transition probabilities are calculated. We examine the temperature and density values for which a phase transition may develop in hot nuclear matter produced in the course of a heavy-ion reaction. 相似文献
15.
The entropy production rate of non-equilibrium systems is studied via the Fokker-Planck equation. This approach, based on the entropy production rate equation given by Schnakenberg from a master equation, requires information on the transition rate of the system under study. We obtain the transition rate from the conditional probability extracted from the Fokker-Planck equation and then derive a new and more operable expression for the entropy production rate. A few examples are presented as applications of our approach. 相似文献
16.
Energy spectra for decaying 2D turbulence in a bounded domain 总被引:1,自引:0,他引:1
We use results derived in the framework of the replica approach to study the liquid-glass thermodynamic transition. The main results are derived without using replicas and applied to the study of the Lennard-Jones binary mixture introduced by Kob and Andersen. We find that there is a phase transition due to the entropy crisis. We compute both analytically and numerically the value of the phase transition point T(K) and the specific heat in the low temperature phase. 相似文献
17.
JiaLin Li Wei Shao JianXin Chen LiangJin Xue 《International Journal of Infrared and Millimeter Waves》2004,25(3):513-521
In this paper, a novel transition, based on the ridged-waveguide together with the microstrip-probe approach, is proposed. With this structure, it overcomes the difficulties in the mounting reproducibility and DC-block restriction of the ridged-waveguide-to-microstrip transition in applications. Centered at 42.5GHz, such a transition, employing Duriod based substrates, has been designed and verified by the HFSS simulator. Also, the simulation results are presented. 相似文献
18.
A non-perturbative approach for the study of the interaction of a hydroxyl (OH) radical with infra-red radiation is presented.
The dressed states and vibrational transition probability of OH radical are defined by a quasi-energy approach (non-perturbative). 相似文献
19.
Fernández LA Gordillo-Guerrero A Martín-Mayor V Ruiz-Lorenzo JJ 《Physical review letters》2008,100(5):057201
We present the first detailed numerical study in three dimensions of a first-order phase transition that remains first order in the presence of quenched disorder (specifically, the ferromagnetic-paramagnetic transition of the site-diluted four states Potts model). A tricritical point, which lies surprisingly near the pure-system limit and is studied by means of finite-size scaling, separates the first-order and second-order parts of the critical line. This investigation has been made possible by a new definition of the disorder average that avoids the diverging-variance probability distributions that plague the standard approach. Entropy, rather than free energy, is the basic object in this approach that exploits a recently introduced microcanonical Monte Carlo method. 相似文献
20.
Damien Simon 《Journal of statistical physics》2011,142(5):931-951
The probability distribution of the current in the asymmetric simple exclusion process is expected to undergo a phase transition
in the regime of weak asymmetry of the jumping rates. This transition was first predicted by Bodineau and Derrida using a
linear stability analysis of the hydrodynamical limit of the process and further arguments have been given by Mallick and
Prolhac. However it has been impossible so far to study what happens after the transition. The present paper presents an analysis
of the large deviation function of the current on both sides of the transition from a Bethe Ansatz approach of the weak asymmetry
regime of the exclusion process. 相似文献