Potential Energy Surface in Deformed Di-Nuclear System

In DNS model, a key point is the calculation of PES because it governs the fusion dynamics and thus determines the optimum excitation energy of the compound nucleus and the optimum bombarding energy. Furthermore, it gives the information about the optimum projectile-target combination leading to a certain super-heavy nucleus.

Molecular Dynamics Study of Interaction between Acrylamide Copolymers and Alumina Crystal

Four acrylamide polymer flocculants, anionic polyacrylamide P（AA-co-AM）, cationic poly- acrylamide P（DMB-co-AM）, nonionic polyacrylamide P（AM）, and hydrophobical polyacry- lamide P（OA-co-AM） have been prepared by copolymerizing with acrylic acid, cationic monomer dimethylethyl （acryloxyethyl） ammonium bromide （DMB） and hydrophobical monomer octadecyl acrylate with acrylamide. The interactions between the flocculants with the （012） surface of alumina crystal （A1203） have been simulated by molecular dynamics method. All the polymers can bind tightly with A1203 crystal, the interaction between the O of polymers and A1 of the （012） surface of A1203 is significantly strong. The order of binding energy is as follows： P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, implying a better flocculation performance of P（DMB-co-AM） than the others. Analy- sis indicates that binding energy is mainly determined by Coulomb interaction. Bonds are found between the O atoms of the polymers and the A1 atoms of A1203. The poly- mers＇ structures deform when they combine with A1203 crystal, but the deformation en- ergies are low and far less than non-bonding energies. Flocculation experiments in sus- pension medium of l%Kaolin show a transmittancy of 90.8% for 6 mg/L P（DMB-co-AM） and 73.0% for P（AM）. The sequence of flocculation performance of four polymers is P（DMB-co-AM）〉P（OA-co-AM）〉P（AA-co-AM）〉P（AM）, which is in excellent agreement with the simulation results of binding energy.

Orbital Ordering Induced by Direct Coulomb Repulsion

We consider the covalence characters of the 3d electron with the eg orbital freedoms and put forward a new mechanism of the orbital ordering （00） based on the direct coulomb repulsion in this article. The results show that the orbital-orbital interaction （OO-I） between the adjacent ions in 180-degree configuration is dominated by the superexchange energy accompanied by a weak orbital-spin coupling, and the OO-I in 90-degree configuration is monitored by the oxygen on-site coulomb repulsion. The ferro-OO is the stable ground state for the one-dimensional chain in the case of the 90-degree configuration.

Quantum heat engine cycle working with a strongly correlated electron system

A new model of a quantum heat engine （QHE） cycle is established, in which the working substance consists of an interacting electrons system. One of our purposes is to test the validity of the second law of thermodynamics by this model, which is more general than the spin-1/2 antiferromagnetic Heisenberg model since it would recover the spin model when the on-site Coulomb interaction U is strong enough. On the basis of quantum mechanics and the first law of thermodynamics, we show no violation of the second law of thermodynamics during the cycle. We further study the performance characteristics of the cycle by investigating in detail the optimal relations of efficiency and dimensionless power output. We find that the efficiency of our engine can be expressed as η = t22/t21 in the large-U limit, which is valid even for a four sites QHE.

Diffusion behavior of polyelectrolytes in dilute solution: coupling effects of hydrodynamic and Coulomb interactions

The diffusion behavior of polyelectrolytes in dilute salt-free solution is studied through a hybrid mesoscale simulation technique that combines the molecular dynamics method and the multiparticle collision dynamics approach.To elucidate the effects of hydrodynamic interactions(HI),we compare results for hydrodynamic and random solvents.When HI are taken into account,we find that the chain diffusivity decreases initially and then increases gradually with the increasing strength of the Coulomb interaction.By contrast,when HI are switched off,the electrostatic-dependent diffusivity shows three distinct regions,and a plateau of approximately constant diffusivity manifests between two decreasing regions.The findings reveal that the dynamics of polyelectrolytes in dilute solution depend on the coupling effects of hydrodynamic and Coulomb interactions,and that these dynamics can be understood by considering the conformational changes of chains,the counterion condensation,and the dynamics of counterions.