Based on the quantum molecular dynamics model,we investigate the dynamical behaviors of the excited nuclear system to simulate the latter stage of heavy ion reactions,which associate with a liquid-gas phase transition...Based on the quantum molecular dynamics model,we investigate the dynamical behaviors of the excited nuclear system to simulate the latter stage of heavy ion reactions,which associate with a liquid-gas phase transition.We try to search a microscopic way to describe the phase transition in realnuclei.The Lyapunov exponent is employed and examined for our purpose.We find out that the Lyapunov exponent is one of good microscopic quantities to describe the phase transition in hot nuclei.Coulomb potential and the finite size effect may give a strong influence on the critical temperature.However,the collision term plays a minor role in the process of the liquid-gas phase transition in finite systems.展开更多
A flashing correlation ratchet model is proposed,in which the transport of Brownian particles driven by additive colored noise of Ornstein-Uhlenbeck type in a flashing ratchet is studied by Monte Carlo simulation.The ...A flashing correlation ratchet model is proposed,in which the transport of Brownian particles driven by additive colored noise of Ornstein-Uhlenbeck type in a flashing ratchet is studied by Monte Carlo simulation.The stationary current vs the noise strength and the correlation time is obtained and analyzed.For a fixed rate of potential flashing,the novel phenomena of current reversal and reentry occur.The conditions for the occurrence of these phenomena are found.The in fluence of the flipping rate is also discussed.This finding might be relevant to the fact that the protein motors with similar structure can move in opposite directions on the same kind of microtubule.展开更多
The directed motion of Brownian particles is generated by a travelling asymmetric potential.The asymptotic behaviour of probability density of the particles at long time is a solitary wave.The Brownian particles can d...The directed motion of Brownian particles is generated by a travelling asymmetric potential.The asymptotic behaviour of probability density of the particles at long time is a solitary wave.The Brownian particles can do work against an external opposing force with high efficiency.The analytical expressions of the solitary wave and the efficiency of the Brownian particles are obtained.The average velocity and the efficiency of the particles depends strongly on the travelling speed and the asymmetry of the potential.展开更多
We study one-and two-neutron transfer reactions in ^(11)Be+^(208)Pb by using the quantum molecular dynamics model.We find that lowering about 1-2 MeV of the potential barrier of ^(208)Pb for fusion is gained when two ...We study one-and two-neutron transfer reactions in ^(11)Be+^(208)Pb by using the quantum molecular dynamics model.We find that lowering about 1-2 MeV of the potential barrier of ^(208)Pb for fusion is gained when two neutrons separated from ^(11)Be enter into ^(208)Pb.Whereas no significant change of potential barrier is found when only the halo neutron separated from ^(11)Be enters into ^(208)Pb.The dynamical interplay between suppression and enhancement effects on the fusion probability in reaction ^(11)Be+^(208)Pb stemming from the easy separation of halo neutron and the long extending of neutron distribution is discussed.展开更多
Within the framework of the two-center shell model,the classically dynamical behaviour of a nucleon in heavy nuclei is investigated when nuclear shape parameters are changed systematically.It is found that there is a ...Within the framework of the two-center shell model,the classically dynamical behaviour of a nucleon in heavy nuclei is investigated when nuclear shape parameters are changed systematically.It is found that there is a good quantum-classical correspondence of nucleonic regular(chaotic)motion so that Bohigas,Giannoni and Schmit conjecture is confirmed once again.展开更多
The result that the process by which the pulses,initially distributed in desoxyribonucleic acid(DNA)molecules can resume its form to localize the large amplitude excitations is proposed.This process may play an import...The result that the process by which the pulses,initially distributed in desoxyribonucleic acid(DNA)molecules can resume its form to localize the large amplitude excitations is proposed.This process may play an important role in the dynamics of localized thermal bubble for the transcription of DNA molecules.展开更多
The fission rate of <sup>240</sup>Pu at its saddle point is obtained by using generalized coherentstate ansatz for large friction case. The numerical results indicate that the quasi-stationary fiss-ion rat...The fission rate of <sup>240</sup>Pu at its saddle point is obtained by using generalized coherentstate ansatz for large friction case. The numerical results indicate that the quasi-stationary fiss-ion rate approaches Kramers’ rate and the transient behaviour agrees with that given in previousstudies. Moreover, the relationship between the first eigenvalue λ<sub>1</sub> and the quasi-stationary fiss-ion rate λ<sub>qs</sub> is derived. In the case of high temperature, we also pay attention to the overshoot-ing.展开更多
基金Supported in part by the National Natural Science Foundation of China under Grant Nos.19775066 and 19975073the Nuclear Industry and Science Foundation of China.
文摘Based on the quantum molecular dynamics model,we investigate the dynamical behaviors of the excited nuclear system to simulate the latter stage of heavy ion reactions,which associate with a liquid-gas phase transition.We try to search a microscopic way to describe the phase transition in realnuclei.The Lyapunov exponent is employed and examined for our purpose.We find out that the Lyapunov exponent is one of good microscopic quantities to describe the phase transition in hot nuclei.Coulomb potential and the finite size effect may give a strong influence on the critical temperature.However,the collision term plays a minor role in the process of the liquid-gas phase transition in finite systems.
基金Supported by the National Natural Science Foundation of China under Grant Nos.19677206 and 19775066the Natural Science Foundation of Hebei Province.
文摘A flashing correlation ratchet model is proposed,in which the transport of Brownian particles driven by additive colored noise of Ornstein-Uhlenbeck type in a flashing ratchet is studied by Monte Carlo simulation.The stationary current vs the noise strength and the correlation time is obtained and analyzed.For a fixed rate of potential flashing,the novel phenomena of current reversal and reentry occur.The conditions for the occurrence of these phenomena are found.The in fluence of the flipping rate is also discussed.This finding might be relevant to the fact that the protein motors with similar structure can move in opposite directions on the same kind of microtubule.
基金Supported by the National Natural Science Foundation of China under Grant Nos.19975073the China Postdoctoral Science Foundation.
文摘The directed motion of Brownian particles is generated by a travelling asymmetric potential.The asymptotic behaviour of probability density of the particles at long time is a solitary wave.The Brownian particles can do work against an external opposing force with high efficiency.The analytical expressions of the solitary wave and the efficiency of the Brownian particles are obtained.The average velocity and the efficiency of the particles depends strongly on the travelling speed and the asymmetry of the potential.
基金the National Natural Science Foundation of China under Grant Nos.19675069 and 19975073.
文摘We study one-and two-neutron transfer reactions in ^(11)Be+^(208)Pb by using the quantum molecular dynamics model.We find that lowering about 1-2 MeV of the potential barrier of ^(208)Pb for fusion is gained when two neutrons separated from ^(11)Be enter into ^(208)Pb.Whereas no significant change of potential barrier is found when only the halo neutron separated from ^(11)Be enters into ^(208)Pb.The dynamical interplay between suppression and enhancement effects on the fusion probability in reaction ^(11)Be+^(208)Pb stemming from the easy separation of halo neutron and the long extending of neutron distribution is discussed.
基金Supported by the China Postdoctoral Science Foundation(1977-11)the National Natural Science Foundation of China under Grant No.19677203。
文摘Within the framework of the two-center shell model,the classically dynamical behaviour of a nucleon in heavy nuclei is investigated when nuclear shape parameters are changed systematically.It is found that there is a good quantum-classical correspondence of nucleonic regular(chaotic)motion so that Bohigas,Giannoni and Schmit conjecture is confirmed once again.
基金Supported by the National Natural Science Foundation of China under Grant No.19677206,and the Nuc-lcar ncdustry and Science Fonudation of China.
文摘The result that the process by which the pulses,initially distributed in desoxyribonucleic acid(DNA)molecules can resume its form to localize the large amplitude excitations is proposed.This process may play an important role in the dynamics of localized thermal bubble for the transcription of DNA molecules.
文摘The fission rate of <sup>240</sup>Pu at its saddle point is obtained by using generalized coherentstate ansatz for large friction case. The numerical results indicate that the quasi-stationary fiss-ion rate approaches Kramers’ rate and the transient behaviour agrees with that given in previousstudies. Moreover, the relationship between the first eigenvalue λ<sub>1</sub> and the quasi-stationary fiss-ion rate λ<sub>qs</sub> is derived. In the case of high temperature, we also pay attention to the overshoot-ing.
