arXiv subjects

Jiulin Du

Publications and source records attributed to Jiulin Du.

At least 55 records · Page 3Linked to original sources

arXiv2014

The rate coefficients of unimolecular reactions in the systems with power-law distributions

The rate coefficient formulae of unimolecular reactions are generalized to the systems with the power-law distributions based on nonextensive statistics, and the power-law rate coefficients are derived in the high and low pressure limits, respectively. The numerical analyses are made of the rate coefficients as functions of the nu-parameter, the threshold energy, the temperature and the number of degrees of freedom. We show that the new rate coefficients depend strongly on the nu-parameter different from one (thus from a Boltzmann-Gibbs distribution). Two unimolecular reactions are taken as application examples to calculate their power-law rate coefficients, which obtained with the nu-parameters slightly different from one can be exactly in agreement with all the experimental studies on these two reactions in the given temperature ranges.

physics.chem-ph↗

arXiv2014

Are power-law distributions an equilibrium distribution or a stationary nonequilibrium distribution?

We examine whether the principle of detailed balance holds for the power-law distributions generated from the general Langevin equation under the generalized fluctuation-dissipation relation (FDR). With the detailed balance and the generalized FDR, we derive analytically the stationary power-law distribution from the Ito's, Stratonovich's and Zwanzig's Fokker-Planck equations, and conclude that the power-law distributions can either be a stationary nonequilibrium distribution or an equilibrium distribution, which depend on information about the form of the diffusion coefficient function, and the existence and uniqueness of an equilibrium state.

cond-mat.stat-mech↗

arXiv2014

The collision theory reaction rate coefficient for power-law distributions

The collision theory for power-law distributions and a generalized collision theory rate coefficient is studied when the reactions take place in nonequilibrium systems with power-law distributions. We obtain the power-law rate coefficient and by numerical analyses we show a very strong dependence of the rate coefficient on the power-law parameter. We find that the power-law collision theory can successfully overcome the two difficulties of Lindemann-Christiansen mechanism. We take three reactions as examples to calculate the pre-exponential factor and yield the values that can be exactly in agreement with those measured in the experimental studies.

cond-mat.stat-mech↗

arXiv2014

The gravitational heat conduction and the hierarchical structure in solar interior

With the assumption of local Tsallis equilibrium, the newly defined gravitational temperature is calculated in the solar interior, whose distribution curve can be divided into three parts, the solar core region, radiation region and convection region, in excellent agreement with the solar hierarchical structure. By generalizing the Fourier law, one new mechanism of heat conduction, based on the gradient of the gravitational temperature, is introduced into the astrophysical system. This mechanism is related to the self-gravity of such self-gravitating system whose characteristic scale is large enough. It perhaps plays an important role in the astrophysical system which, in the solar interior, leads to the heat accumulation at the bottom of the convection layer and then motivates the convection motion.

physics.gen-ph↗

arXiv2014

Escape rate for the power-law distribution in low-to-intermediate damping

Escape rate in the low-to-intermediate damping connecting the low damping with the intermediate damping is established for the power-law distribution on the basis of flux over population theory. We extend the escape rate in the low damping to the low-to-intermediate damping, and get an expression for the power-law distribution. Then we apply the escape rate for the power-law distribution to the experimental study of the excited-state isomerization, and show a good agreement with the experimental value. The extra current and the improvement of the absorbing boundary condition are discussed.

cond-mat.stat-mech↗

arXiv2014

Kramers escape rate in overdamped systems with the power-law distribution

Kramers escape rate in the overdamped systems with the power-law distribution is studied. By using the mean first passage time, we derive the escape rate for the power-law distribution and obtain the Kramers' infinite barrier escape rate in this case. It is shown that the escape rate for the power-law distribution extends the Kramers' overdamped result to the relatively low barrier. Furthermore, we apply the escape rate for the power-law distribution to the unfolding of titin and show a better agreement with the experimental rate than the traditional escape rate.

cond-mat.stat-mech↗

arXiv2013

The power-law reaction rate coefficient for an elementary bimolecular reaction

The power-law TST reaction rate coefficient for an elementary bimolecular reaction is studied when the reaction takes place in a nonequilibrium system with power-law distributions. We derive a generalized TST rate coefficient, which not only depends on a power-law parameter but also on the reaction coordinate frequency of transition state. The numerical analyses show a very strong dependence of TST rate coefficient on the power-law parameter, and clearly indicate that a tiny deviation from unity in the parameter (thus from the Boltzmann-Gibbs distribution) would result in significant changes in the rate coefficient. We take an elementary F+H2 reaction as an application example to calculate the reaction rate coefficient, and yield the rate values being exactly agreement with the measurement values in all the experimental studies in temperature range 190~765K.

physics.chem-ph↗

arXiv2013

The mean first passage time in an energy-diffusion controlled regime with power-law distributions

Based on the mean first passage time (MFPT) theory, we derive the expression of the MFPT in the energy-diffusion controlled regime with a power-law distribution. We discuss the finite barrier effect (i.e. thermal energy is not small with respect to the potential barrier) and compare it with the Kramers infinite barrier result both in the power-law distribution and in a Maxwell-Boltzmann distribution. It is shown that the MFPT with the power-law distribution extends the Kramers' low damping result to the relatively low barrier. We pay attention to the energy-diffusion controlled regime which is of great interest in the context of Josephson junctions, and study how the power-law parameter affects the current distribution function in the experiment of Josephson junctions.

cond-mat.stat-mech↗

arXiv2013

Transport coefficients in Lorentz plasmas with the power-law kappa-distribution

Transport coefficients in Lorentz plasma with the power-law kappa-distribution are studied by means of using the transport equation and macroscopic laws of Lorentz plasma without magnetic field. Expressions of electric conductivity, thermoelectric coefficient and thermal conductivity for the power-law kappa-distribution are accurately derived. It is shown that these transport coefficients are significantly modified by the kappa-parameter, and in the limit of the parameter kappa to infinit they are reduced to the standard forms for a Maxwellian distribution.modified

physics.plasm-ph↗

arXiv2013

Electronic and optical properties of C-N-codoped TiO2: A first-principles GGA+U investigation

Electronic structures and optical properties of C-N-codoped anatase TiO2 were calculated by using GGA+U method based on the density functional theory. The calculated results showed that the N-doped, C-doped, and C-N-codoped TiO2 produced 2p states in band gap, and the band gaps of the three doped systems decreased compared with the pure TiO2. According to the optical results, the band edges of the three doped systems shifted to the long wavelength region, and the visible optical absorption from 450 to 800 nm was observed. Moreover, the visible light response of C-N-codoped TiO2 was better than the C or N single doped TiO2, indicating that there was a synergistic effect for the C-N-codoped TiO2, which offseted the deficiencies of C or N-doped TiO2.

cond-mat.mtrl-sci↗

arXiv2012

Power-law behaviors from the two-variable Langevin equation: Ito's and Stratonovich's Fokker-Planck equations

We study power-law behaviors produced from the stochastically dynamical system governed by the well-known two-variable Langevin equations. The stationary solutions of the corresponding Ito's, Stratonovich's and the Zwanzig's (the backward Ito's) Fokker-Planck equations are solved under a new fluctuation-dissipation relation, which are presented in a unified form of the power-law distributions with a power index containing two parameter kappa and sigma, where kappa measures a distance away from the thermal equilibrium and sigma distinguishes the above three forms of the Fokker-Planck equations. The numerical calculations show that the Ito's, the Stratonovich's and the Zwanzig's form of the power-law distributions are all exactly the stationary solutions based on the two-variable Langevin equations.

cond-mat.stat-mech↗

arXiv2012

Dust-acoustic waves and stability in the permeating dusty plasma: I. Maxwellian distribution

The dust-acoustic waves and their stability in the permeating dusty plasma with the Maxwellian velocity distribution are investigated. We derive the dust-acoustic wave frequency and instability growth rate in two limiting physical cases that the thermal velocity of the flowing dusty plasma is (a) much larger than, and (b) much smaller than the phase velocity of the waves. We find that the stability of the waves depend strongly on the velocity of the flowing dusty plasma in the permeating dusty plasma. The numerical analyses are made based on the example that a cometary plasma tail is passing through the interplanetary space plasma. We show that, in case (a), the waves are generally unstable for any flowing velocity, but in case (b), the waves become unstable only when the wave number is small and the flowing velocity is large. When the physical conditions are between these two limiting cases, we gain a strong insight into the dependence of the stability criterions on the physical conditions in the permeating dusty plasma.

physics.plasm-ph↗

arXiv2012

Secondary electron emissions and dust charging currents in the nonequilibrium dusty plasma with power-law distributions

We study the secondary electron emissions induced by the impact of electrons on dust grains and the resulting dust charging processes in the nonequilibrium dusty plasma with power-law distributions. We derive new expressions of the secondary emitted electron flux and the dust charging currents that are generalized by the power-law q-distributions, where the nonlinear core functions are numerically studied for the nonextensive parameter q. Our numerical analyses show that the power-law q-distribution of the primary electrons has a significant effect on the secondary emitted electron flux as well as the dust charging currents, and this effect depends strongly on the ratio of the electrostatic potential energy of the primary electrons at the dust grain's surface to the thermodynamic energy, implying that a competition in the dusty plasma between these two energies plays a crucial role in this novel effect.

physics.plasm-ph↗

arXiv2012

Electronic structure and enhanced visible light absorption of N, B-codoped TiO2

We present the GGA+U calculations to investigate the electronic structure and visible light absorption of the N, B-codoped anatase TiO2. The NsBi (substitutional N, interstitial B) codoped TiO2 produces significant Ti 3d and N 2p mid-gap states when the distance of N and B atoms is far, and the NiBi (interstitial N and B) and NsBs (substitutional N and B) codoped TiO2 prefer to form localized p states at 0.3-1.2 eV above the valence band maximum. Further, the optical band edges of the three codoped systems shift slightly to the visible region, but only the far distance NsBi codoped TiO2 shows an obvious visible optical transition. These results indicate that the NsBi codoped TiO2 has a dominant contribution to the visible absorption of the N, B-codoped TiO2.

cond-mat.mtrl-sci↗

arXiv2012

First-principles study of electronic structures and optical properties of Cu, Ag, and Au-doped anatase TiO2

We perform first-principles calculations to investigate the band structure, density of states, optical absorption, and the imaginary part of dielectric function of Cu, Ag, and Au-doped anatase TiO2 in 72 atoms systems. The electronic structure results show that the Cu incorporation can lead to the enhancement of d states near the uppermost of valence band, while the Ag and Au doping cause some new electronic states in band gap of TiO2. Meanwhile, it is found that the visible optical absorptions of Cu, Ag, and Au-doped TiO2, are observed by analyzing the results of optical properties,.which locate in the region of 400-1000 nm. The absorption band edges of Cu, Ag, and Au-doped TiO2 shift to the long wavelength region compared with the pure TiO2. Furthermore, according to the calculated results, we propose the optical transition mechanisms of Cu, Ag, and Au-doped TiO2, respectively. Our results show that the visible light response of TiO2 can be modulated by substitutional doping of Cu, Ag, and Au.

cond-mat.mtrl-sci↗

arXiv2012

Dust charging processes in the nonequilibrium dusty plasma with nonextensive power-law distribution

The dust charging processes in the collections of electrons and ions in the nonequilibrium dusty plasma with power-law distributions are investigated on the basic of a new q-distribution function theory in nonextensive statistics. Electrons and ions obey the power-law distributions and are with q-parameters different from each other. We derive the generalized formulae for the dust charging currents in which the nonextensive effects play roles. Further we investigate the dust charging processes taking place in the homogeneous dusty plasma where only the particle velocities are power-law distributions and in the dust cloud plasma where the particle velocities and densities are both power-law distributions. By numerical analyses, we show that the nonextensive power-law distributions of electrons and ions have significant effects on the dust charging processes in the nonequilibrium dusty plasma.

physics.plasm-ph↗

arXiv2012

Energy distribution and energy fluctuation in Tsallis statistics

The energy distribution and the energy fluctuation in the Tsallis canonical ensemble are studied with the OLM formalism but following a new way. The resulting formula for the energy fluctuation is not the same as that in previous work [Liu L.Y. and Du J.L., Physica A 387(2008)5417]. In discussing the application of an ideal gas, we find that the energy fluctuation can not be negligible in the thermodynamic limit, showing the ensemble nonequivalence for this case in Tsallis statistics. We investigate the energy fluctuation with a Tsallis generalized canonical distribution studied by Plastino and Plastino [Phys. Lett. A 193(1994)140] for describing a system in contact with a finite heath bath. For this situation, the two formulae for the energy fluctuation are shown to be equivalent, while the nonextensive parameter q plays a very important role.

cond-mat.stat-mech↗

arXiv2012

Dust-acoustic waves and stability in the permeating dusty plasma: II. Power-law distributions

The dust-acoustic waves and their stability driven by a flowing dusty plasma when it cross through a static (target) dusty plasma (the so-called permeating dusty plasma) are investigated when the components of the dusty plasma obey the power-law q-distributions in nonextensive statistics. The frequency, the growth rate and the stability condition of the dust-acoustic waves are derived under this physical situation, which express the effects of the nonextensivity as well as the flowing dusty plasma velocity on the dust-acoustic waves in this dusty plasma. The numerical results illustrate some new characteristics of the dust-acoustic waves, which are different from those in the permeating dusty plasma when the plasma components are the Maxwellian distribution. In addition, we show that the flowing dusty plasma velocity has a significant effect on the dust-acoustic waves in the permeating dusty plasma with the power-law q-distribution.

physics.plasm-ph↗