The dipole moment, total energy, atomic charge, orbital population and orbital energy of four representative combination models of the favorable growth unit Al6（OH）18（H2O）6 of Al（OH）3 crystals precipitating are ...The dipole moment, total energy, atomic charge, orbital population and orbital energy of four representative combination models of the favorable growth unit Al6（OH）18（H2O）6 of Al（OH）3 crystals precipitating are calculated by ab initio at RHF/STO-3G, RHF/3-21G, RHF/6-31G levels and DFT at RB3LYP/STO-3G, RB3LYP/3-21G, RB3LYP/6-31G levels with Dipole & Sphere solvent model. The effect of various combination models on Van der Waals force is analyzed using dipole moment and molecular radius, and that on chemical bond force is analyzed using total energy, orbital population and orbital energy.展开更多
At the molecular mechanic level, the capability of a set of 24 molecular cage-like structures, the spherophanes, to store hydrogen molecules has been studied. Two main factors have been found to govern their storage c...At the molecular mechanic level, the capability of a set of 24 molecular cage-like structures, the spherophanes, to store hydrogen molecules has been studied. Two main factors have been found to govern their storage capacity： the volume of their cavity and the potential energy barriers at the different openings at the surface of the cage. Calculations have shown that 13H2 molecules could be stored inside the thiaspherophane, Th4S, whose mean radius is 10A and the resulting complex （H2）I3@Th4S is found to be stable. The results show that it would be very difficult to store more than 2H2 inside the smallest spherophane, Sp4, whose mean radius is 7.7A. The mean intermolecular distance Hz-Hz and the mean bond length H-H have been found to decrease when the number of imprisoned hydrogen molecules increases. It has also been found that the encapsulated H2 molecules form clusters of different symmetries on which the formation energy depends strongly. Even with 13H2 molecules inside Th4S, the weight percentage is still small, 2.57%. The largest obtained wt% is 3.22% in the case of Th5S（CH3）10.展开更多
Results of thermal expansion prediction from atomic scale for metastable liquid metals are reported herein. Three pure liquid metals Ni, Fe, and Cu together with ternary Ni60Fe20Cu20 alloy are used as models. The pair...Results of thermal expansion prediction from atomic scale for metastable liquid metals are reported herein. Three pure liquid metals Ni, Fe, and Cu together with ternary Ni60Fe20Cu20 alloy are used as models. The pair distribution functions were em- ployed to monitor the atomic structure. This indicates that the simulated systems are ordered in atomic short range and disor- dered in long range. The thermal expansion coefficient was computed as functions of temperature and atom cutoff radius, which tends to maintain a constant when the cutoff radius increases to approximately 15A. In such a case, slightly more than 1000 atoms are required for liquid Ni, Cu, Fe and Ni60Fe20Cu20 alloy, that is, the macroscopic thermal expansion can be pre- dicted from the volume change of such a tiny cell. Furthermore, the expansion behaviors of the three types of atoms in liquid Ni60Fe20Cu20 alloy are revealed by the calculated partial expansion coefficient. This provides a fundamental method to predict the macroscopic thermal expansion from the atomic scale for liquid alloys, especially in the undercooled regime.展开更多
We have investigated the general relativistic field equations for neutron stars.We find that there are solutions for the equilibriummass distribution without a maximum mass limit.The solutions correspond to stars with...We have investigated the general relativistic field equations for neutron stars.We find that there are solutions for the equilibriummass distribution without a maximum mass limit.The solutions correspond to stars with a void inside their centers.In thesesolutions,the mass density and pressure increase first from zero at the inner radius to a peak and then decrease to zero at the outerradius.With the change of the void boundary,the mass and particle number of the star can approach infinity.Neutron stars withlarge masses can remain stable and do not collapse into black holes.展开更多
A highly focused beam with spot radius of around 1 ktm and enhanced light intensity is obtained by using an open hollow cone. Two-dimensional and three-dimensional finite-difference time-domain simulations are perform...A highly focused beam with spot radius of around 1 ktm and enhanced light intensity is obtained by using an open hollow cone. Two-dimensional and three-dimensional finite-difference time-domain simulations are performed for clarifying light propagation characteristics and the cone geometry dependence of the cone-focused laser light. Two important parameters characterizing the cone-focusing effect are introduced, which are opening angle and cone tip size. By changing these parameters, the laser intensification, field spatial distribution at the cone tip and the near-field transmission can be controlled. Understanding this is quite important in designing the optimum cone shape for fast ignition and determining the basis for using hollow cone targets as devices for generating high energy charged particles.展开更多
基金Project(50374078) supported by the National Natural Science Foundation of China Project(G1999064902) supported bythe National Basic Research Programof China
文摘The dipole moment, total energy, atomic charge, orbital population and orbital energy of four representative combination models of the favorable growth unit Al6（OH）18（H2O）6 of Al（OH）3 crystals precipitating are calculated by ab initio at RHF/STO-3G, RHF/3-21G, RHF/6-31G levels and DFT at RB3LYP/STO-3G, RB3LYP/3-21G, RB3LYP/6-31G levels with Dipole & Sphere solvent model. The effect of various combination models on Van der Waals force is analyzed using dipole moment and molecular radius, and that on chemical bond force is analyzed using total energy, orbital population and orbital energy.
文摘At the molecular mechanic level, the capability of a set of 24 molecular cage-like structures, the spherophanes, to store hydrogen molecules has been studied. Two main factors have been found to govern their storage capacity： the volume of their cavity and the potential energy barriers at the different openings at the surface of the cage. Calculations have shown that 13H2 molecules could be stored inside the thiaspherophane, Th4S, whose mean radius is 10A and the resulting complex （H2）I3@Th4S is found to be stable. The results show that it would be very difficult to store more than 2H2 inside the smallest spherophane, Sp4, whose mean radius is 7.7A. The mean intermolecular distance Hz-Hz and the mean bond length H-H have been found to decrease when the number of imprisoned hydrogen molecules increases. It has also been found that the encapsulated H2 molecules form clusters of different symmetries on which the formation energy depends strongly. Even with 13H2 molecules inside Th4S, the weight percentage is still small, 2.57%. The largest obtained wt% is 3.22% in the case of Th5S（CH3）10.
基金supported by the National Natural Science Foundation of China(Grant Nos.51474175,51271150 and 51327901)the Program for New Century Excellent Talents and NPU Foundation for Fundamental Research
文摘Results of thermal expansion prediction from atomic scale for metastable liquid metals are reported herein. Three pure liquid metals Ni, Fe, and Cu together with ternary Ni60Fe20Cu20 alloy are used as models. The pair distribution functions were em- ployed to monitor the atomic structure. This indicates that the simulated systems are ordered in atomic short range and disor- dered in long range. The thermal expansion coefficient was computed as functions of temperature and atom cutoff radius, which tends to maintain a constant when the cutoff radius increases to approximately 15A. In such a case, slightly more than 1000 atoms are required for liquid Ni, Cu, Fe and Ni60Fe20Cu20 alloy, that is, the macroscopic thermal expansion can be pre- dicted from the volume change of such a tiny cell. Furthermore, the expansion behaviors of the three types of atoms in liquid Ni60Fe20Cu20 alloy are revealed by the calculated partial expansion coefficient. This provides a fundamental method to predict the macroscopic thermal expansion from the atomic scale for liquid alloys, especially in the undercooled regime.
基金supported by the National Natural Science Foundation of China (Grant No. 10974107)
文摘We have investigated the general relativistic field equations for neutron stars.We find that there are solutions for the equilibriummass distribution without a maximum mass limit.The solutions correspond to stars with a void inside their centers.In thesesolutions,the mass density and pressure increase first from zero at the inner radius to a peak and then decrease to zero at the outerradius.With the change of the void boundary,the mass and particle number of the star can approach infinity.Neutron stars withlarge masses can remain stable and do not collapse into black holes.
基金supported by the National Basic Research Program of China(Grant No.61359020101-3)the National High Technology ResearchDevelopment Program for Inertial Confinement Fusion of China
文摘A highly focused beam with spot radius of around 1 ktm and enhanced light intensity is obtained by using an open hollow cone. Two-dimensional and three-dimensional finite-difference time-domain simulations are performed for clarifying light propagation characteristics and the cone geometry dependence of the cone-focused laser light. Two important parameters characterizing the cone-focusing effect are introduced, which are opening angle and cone tip size. By changing these parameters, the laser intensification, field spatial distribution at the cone tip and the near-field transmission can be controlled. Understanding this is quite important in designing the optimum cone shape for fast ignition and determining the basis for using hollow cone targets as devices for generating high energy charged particles.
