A theoretical study of fragmentation dynamics of water dimer by proton impact

To investigate the collision processes of proton with the water dimer(H_(2)O)_(2)at 50 e V,the time-dependent density functional theory coupled with molecular dynamics nonadiabatically is applied.Six specific collision orientations with various impact parameters are considered.The reaction channels,the mass distribution and the fragmentation mass spectrum are explored.Among all launched samples,the probability of the channel of non-charge transfer scattering and charge transfer scattering is about 80%,hinting that the probability of fragmentation is about 20%.The reaction channel of proton exchange process 2 is taken as an example to exhibit the detailed microscopic dynamics of the collision process by inspecting the positions,the respective distance,the number of loss of electrons and the evolution of the electron density.The study of the mass distribution and the fragmentation mass spectrum shows that among all possible fragments,the fragment with mass 36 has the highest relative abundance of 65%.The relative abundances of fragments with masses 1,35,and 34are 20%,13%,and 1.5%,respectively.For the total electron capture cross section,the present calculations agree with the available measurements and calculations over the energy range from 50 e V to 12 ke V.

Probing the density dependence of the symmetry energy with central heavy ion collisions

An improved isospin dependent Boltzmann Langevin model,in which the inelastic channels and momentum dependent interactions are incorporated,is used to investigate the high-density behavior of nuclear symmetry energy.By taking several forms of nuclear symmetry energy,we calculate the time evolutions of neutron over proton ratio,π multiplicity and π-/π+ ratio,and the kinetic energy and transverse momentum spectra of π-/π+ ratio in the heavy ion collisions at 400A MeV.It is found that the neutron over proton ratio and π-/π+ ratio are very sensitive to the nuclear symmetry energy,and the π-is more sensitive to the nuclear symmetry energy than the π+.A supersoft symmetry energy results in a larger π-/π+ ratio.

Production of heavy neutron-rich nuclei with radioactive beams in multinucleon transfer reactions

The production mechanism of heavy neutronrich nuclei is investigated by using the multinucleon transfer reactions of ^(136;148)Xe+^(208)Pb and ^(238)U+^(208)Pb in the framework of a dinuclear system model. The evaporation residual cross sections of target-like fragments are studied with the reaction system ^(148)Xe+^(208)Pb at near barrier energies. The results show that the final isotopic production cross sections in the neutron-deficient side are very sensitive to incident energy while it is not sensitive in the neutron-rich side. Comparing the isotopic production cross sections for the reactions of ^(208)Pb bombarded with stable and radioactive projectiles, we find that neutron-rich radioactive beams can significantly increase the production cross sections of heavy neutron-rich nuclei.

Excitation and Ionization of Ethylene by Charged Projectiles

用时间依赖者本地人密度近似，适用于原子价电子， non-adiabatically 联合了到离子的分子的动力学，在乙烯之间的碰撞过程和快控告的射弹以显微镜的方法被学习。电离上的离子的运动的影响被探索显示出同时对待自由的电子、离子的度的重要性。逃离的电子的数字，电离可能性被获得。而且，在不同方向的离子的延期显示出不同模式，这被发现。[从作者抽象]

Theoretical investigations of collision dynamics of cytosine by low-energy (150-1000 eV) proton impact

Using a real-space real-time implementation of time-dependent density functional theory coupled to molecular dynamics(TDDFT-MD)nonadiabatically,we theoretically study both static properties and collision process of cytosine by 150-1000 eV proton impact in the microscopic way.The calculated ground state of cytosine accords well with experiments.It is found that proton is scattered in any case in the present study.The bond break of cytosine occurs when the energy loss of proton is larger than 22 eV and the main dissociation pathway of cytosine is the breaks of C1N2 and N8H10.In the range of 150 eV≤Ek≤360 eV,when the incident energy of proton increases,the excitation becomes more violent even though the interaction time is shortened.While in the range of 360 eV<Ek≤q 1000 eV,the excitation becomes less violent as the incident energy of proton increases,indicating that the interaction time dominates mainly.We also show two typical collision reaction channels by analyzing the molecular ionization,the electronic density evolution,the energy loss of proton,the vibration frequency and the scattering pattern detailedly.The result shows that the loss of electrons can decrease the bond lengths of C3N8 and C5N6 while increase the bond lengths of C4H11,C5H12 and C4C5 after the collision.Furthermore,it is found that the peak of the scattering angle shows a little redshift when compared to that of the loss of kinetic energy of proton.

Quantum Dissipative Threshold and Its Effect on Decay of Metastable State

The coupling between system and reservoir is considered to be linear in the coordinates of the bath but nonlinear in the system's coordinate. A dissipative threshold is observed at finite temperatures due to nonlinear dissipation. The quantum decay rate of a metastable state including higher-order expanded terms of the coupling form function is proposed, which can be strongly decreased at finite temperatures when the quantum dissipative threshold is added to the saddle point of the potential.

Coulomb effects on the formation of proton halo nuclei

This paper makes some qualitative and quantitative analyses about halo formation rules of some mirror nuclei with the relativistic mean-field （RMF） theory and the Woods Saxon mean-field model. By analysing two opposite effects of Coulomb interaction on the proton halo formation, it finds that the energy level shift has a larger contribution than that of the Coulomb barrier when the mass number A is small, the hindrance of the Coulomb barrier becomes more obvious with the increase of the mass number A, and the overall effect of the Coulomb interaction almost disappears when A ≈ 39 as its two effects counteract with each other.

Fragmentation Cross Sections of ^12C on Different Targets at Beam Energies from 50 to 100 MeV/Nucleon

The fragmentation cross sections of reactions ^12C＋^2H, ^12C, ^14N, ^16O at beam energies from 50 to 100 MeV/nucleon are investigated using the isospin-dependent Boltzmann-Langevin equation model. It is found that fragment species increase approximately with the increasing target mass. The fragment species and some fragments production cross sections in reactions of ^12C＋^12C, ^14N, ^16O show an obvious variation at the beam energies from 50 to 80 MeV/nucleon. However the calculated fragment production cross sections do not change much when the incident energy increases from 80 to 100 MeV/nucleon.

Collision site effect on the radiation dynamics of cytosine induced by proton

By combing the time-dependent density functional calculations for electrons with molecular dynamics simulations for ions(TDDFT-MD)nonadiabatically in real time,we investigate the microscopic mechanism of collisions between cytosine and low-energy protons with incident energy ranging from 150 e V to 1000 e V.To explore the effects of the collision site and the proton incident energy on irradiation processes of cytosine,two collision sites are specially considered,which are N and O both acting as the proton receptors when forming hydrogen bonds with guanine.Not only the energy loss and the scattering angle of the projectile but also the electronic and ionic degrees of freedom of the target are identified.It is found that the energy loss of proton increases linearly with the increase of the incident energy in both situations,which are14.2%and 21.1%of the incident energy respectively.However,the scattering angles show different behaviors in these two situations when the incident kinetic energy increases.When proton collides with O,the scattering angle of proton is larger and the energy lost is more,while proton captures less electrons from O.The calculated fragment mass distribution shows the high counts of the fragment mass of 1,implying the production of H+fragment ion from cytosine even for proton with the incident energy lower than keV.Furthermore,the calculated results show that N on cytosine is easier to be combined with low-energy protons to form NH bonds than O.

Time-Averaged Behaviour at the Critical Parameter Point of Transition to Spatiotemporal Chaos

A time-averaged behaviour is found to be important for investigating the critical behaviour in parameter space for the transition from temporal chaos to spatiotemporal chaos by using an energy representation. Considering any wave solution as a superposition of the steady wave with its perturbation wave, we find that when approaching the critical parameter point the averaged positive interaction energy for the k = 1 mode becomes competitive with the negative one, with the summation displaying a scaling behaviour of power law.

Polymorphism and Flexibility of DNA in Alcohols

Molecular dynamics simulations are performed to investigate the polymorphism and flexibility of DNA in water,ethylene glycol(EG)and ethanol(EA)solutions.DNA in EG resembles the structure of DNA in water exhibiting B-DNA.In contrast,the DNA is an A-DNA state in the EA.We demonstrate that one important cause of these A$\leftrightarrow$B state changes is the competition between hydration and direct cation coupling to the phosphate groups on DNA backbones.To DNA structural polymorphism,it is caused by competition between hydration and cation coupling to the base pairs on grooves.Unlike flexible DNA in water and EA,DNA is immobilized around the canonical structure in EG solution,eliminating the potential biological effects of less common non-canonical DNA sub-states.

Controlled Teleportation of an Arbitrary Multi-Qudit State in a General Form with d-Dimensional Greenberger-Horne-Zeilinger States

A general scheme for controlled teleportation of an arbitrary multi-qudit state with d-dimensional Greenberger- Horne--Zeilinger （GHZ） states is proposed. For an arbitrary m-qudit state, the sender Alice performs m generalized Bell-state projective measurements on her 2m qudits and the controllers need only take some single-particle measurements. The receiver Charlie can reconstruct the unknown m-qudit state by performing some single-qudit unitary operations on her particles if she cooperates with all the controllers. As the quantum channel is a sequence of maximally entangled GHZ states, the intrinsic efticiency for qudits in this scheme approaches 100% in principle.

First-principle study of Mg adsorption on Si(111) surfaces

We have carried out first-principle calculations of Mg adsorption on Si（111） surfaces. Different adsorption sites and coverage effects have been considered. We found that the threefold hollow adsorption is energy-favoured in each coverage considered, while for the clean Si（111） surface of metallic feature, we found that 0.25 and 0.5 ML Mg adsorption leads to a semiconducting surface. The results for the electronic behaviour suggest a polarized covalent bonding between the Mg adatom and Si（111） surface.

Measurement of inner surface roughness of capillary by an x-ray reflectivity method

The inner surface roughness of a capillary is investigated by the reflectivity of x-rays penetrating through the capillary. The results are consistent with the data from atomic force microscope （AFM）. The roughness measured by this new method can reach the order of angstroms with high quality capillaries.

Simulation of x-ray transmission through an ellipsoidal capillary

This paper develops a simulation program for x-ray transmission in an ellipsoidal capillary based on a ray-tracing method. The influence of the parameters of ellipsoidal capillary and x-ray energy on transmission efficiency, full width at half maximum and power density gain of x-ray beams through an ellipsoidal capillary was analysed by this program. It shows that the particular rules of the ellipsoidai capillary x-ray lens are different from the polycapillary lens. Furthermore, this analysis method can be applied to the optimized design of ellipsoidal capillary.

Generation of Multiphoton Entangled States with Linear Optical Elements

我们建议没有诉诸，产生三光子、四光子的纠缠的状态的一个线性光协议纠缠了来源。在这个协议的安装由三横梁 splitters 和二个一半波浪盘子组成。我们能与 postselection 获得三光子、四光子的纠缠的状态，就象另外的协议。这个协议有高效率的优点并且比其它更可行。[从作者抽象]

Melting Transition of Small Aluminium Clusters Al11-20

小铝簇 Al11-20 的热能力与实验许多身体 Gupta 潜力用 MDsimulation 被调查。当 Al15-18 的热能力显示渐渐的融化转变时，一些簇 Al-11， Al-12， Al-13 和 Al-19 的热能力显示出明确的山峰。异构体的系列获得了由熄灭 MD 轨道为那些结果给好解释。

Isospin Effects of Threshold Energy of Radial Flow in Heavy Ion Collisions

在在中央碰撞的 Ca-40 + Ca-40 和 Ca-48+ Ca-48 的反应的光线的流动的阀值精力在 isospin 依赖者量以内被调查由使用对称精力的三种不同形式的分子的动力学模型。neutron-richsystem 有光线的流动的更小的阀值精力，这数量取决于对称潜力的形式，这被发现。光线的流动的阀值精力能提供一个新方法决定不对称的原子物质的对称精力，这被显示。

Angle-Dependent Irradiation of C_(4) in Femtosecond Laser Pulses

We study the angle-dependent irradiation of linear C_(4) in the strong femtoeecond laser pulses with the help of time-dependent local density approximation applied to valence electrons,coupled non-adiabatically to molecular dynamics of ions.It is found that the excitation of C_(4) including the electrons and ions has a strong relation to the angle between the laser polarization and the internuclear axis of C4.The ionization yield decreases when theangle ranges from 0 to π/2.A clear suppression in the ionization yield is found when the laser polarization is perpendicular to the internuclear axis of C_(4).We track the dynamic motion of ionized C_(4) even in the relaxation time.It shows that the ionized C_(4) keeps on oscillating without fragmenting after the irradiation in different cases,while it is more excited when the laser polarization is along the internuclear axis.Furthermore,it is found that the change of the ELF takes place mainly in the xy plane and xz plane and the electron ejection mainly comes from the middle two atoms for the θ =0 case.