摘要：
The electronic structures of small sulfur clusters, S2– S12, are calculated using the ab initio self-consistent discrete variational local-density-functional method, and the calculated ionization potential curve is in good agreement with that from experiment in the range from S2 to S8, and the calculated ionization potentials of clusters from S9 to S12 are reliably predicted where measurements are lacking. We suggest that the different mixtures of atomic orbitals 3s and 3p on the highest occupied molecular orbitals for different clusters are related to the change of ionization potential with the cluster size. In addition, we point out that the two sulfur dimers in S4 are bound by the van der Waals force.
摘要：
An analytical study is performed to examine the influence of causally limited viscosity on the stability properties of an isothermal accretion disk. We find that the stability and propagating properties of three kinds of oscillation mode in the disk are different from those in the conventional viscosity case, if the viscosity is modified to follow causality. The viscous mode is still stable throughout the disk, but it is no longer a standing wave. It propagates inward with a damping rate proportional to the viscosity parameter α. The two inertial-acoustic modes are no longer complex conjugates of one another. Their stability and propagating properties are different. The outward-moving mode is unstable throughout the disk, while the inward-moving mode is unstable in the outer disk but stable in the inner disk when the Mach number of accretion flow is larger than a critical value. We estimate that this critical Mach number is ∼0.4 if a revised diffusion-type viscosity is adopted and ∼0.25 if a revised α-viscosity is adopted.
作者机构：
HUAZHONG NORMAL UNIV,INST PARTICLE PHYS,WUHAN 430070,PEOPLES R CHINA.;S CENT COLL NATL,WUHAN 430074,PEOPLES R CHINA.;[YANG, J] ACAD SINICA,INST HIGH ENERGY PHYS,BEIJING 100039,PEOPLES R CHINA.
通讯机构：
[YANG, J] A;ACAD SINICA,INST HIGH ENERGY PHYS,BEIJING 100039,PEOPLES R CHINA.
作者机构：
NATL LAB LASER TECHNOL,WUHAN 430074,PEOPLES R CHINA;HUAZHONG NORMAL UNIV,DEPT PHYS,WUHAN 430070,PEOPLES R CHINA;[LI, GX] CCAST,WORLD LAB,POB 8730,BEIJING 100080,PEOPLES R CHINA.
通讯机构：
[LI, GX] C;CCAST,WORLD LAB,POB 8730,BEIJING 100080,PEOPLES R CHINA.
摘要：
We have studied the steady-state behavior of a V configuration three-level atom driven by a single-mode laser field in a broadband squeezed vacuum bath. The influences of the bath and the relative directions of the atomic dipole moments are discussed.
期刊：
JOURNAL OF PHYSICS-CONDENSED MATTER,1994年6(41):8539-8547 ISSN：0953-8984
通讯作者：
XIAO, CY
作者机构：
CENT CHINA NORMAL UNIV,DEPT PHYS,WUHAN 430070,PEOPLES R CHINA.;UNIV SCI & TECHNOL CHINA,CTR FUNDAMENTAL PHYS,HEFEI 230026,PEOPLES R CHINA.;E CHINA INST TECHNOL,DEPT APPL PHYS,NANJING 210014,PEOPLES R CHINA.;UNIV SCI & TECHNOL CHINA,DEPT MODERN PHYS,HEFEI 230026,PEOPLES R CHINA.;[XIAO, CY] CHINA CTR ADV SCI & TECHNOL,WORLD LAB,POB 8730,BEIJING 100080,PEOPLES R CHINA.
摘要：
First-principles studies are carried out on the electronic structure and Compton profile for the low-symmetry system of calcium dihydride using the discrete variational local-density-functional method with embedded cluster model. The results demonstrate that, with the ionic bonding picture, experimental data from photoelectron spectroscopy with both x-rays and synchrotron radiation and from Compton profile measurements can be reasonably understood. Based on the bonding character revealed in the electronic structure, we suggest that CaH<inf>2</inf> doped with a monovalent element could be a superconductor.
期刊：
Monthly Notices of the Royal Astronomical Society,1994年270(1):131-137 ISSN：0035-8711
通讯作者：
YU, WF
作者机构：
[YANG, LT; WU, XB; YU, WF] HUAZHONG NORMAL UNIV,INST ASTROPHYS,WUHAN 430070,PEOPLES R CHINA.;[YU, WF] INST HIGH ENERGY PHYS,HIGH ENERGY ASTROPHYS LAB,BEIJING 100039,PEOPLES R CHINA.
通讯机构：
[YU, WF] I;INST HIGH ENERGY PHYS,HIGH ENERGY ASTROPHYS LAB,BEIJING 100039,PEOPLES R CHINA.
关键词：
accretion, accretion discs;instabilities;MHD
摘要：
The stability of an isothermal magnetized accretion disc with radial viscous force is examined in this paper. We confirm the former conclusion that viscous stress acting in the radial direction damps the radial oscillations. We also find that consideration of the radial viscosity does not give rise to any new mode of instability. The radial magnetic field is important to disc instability if the vertical component of the magnetic field is zero.
摘要：
In this paper, we have investigated the influence of the counter-rotating terms on the squeezing of light in the two-photon Jaynes-Cummings model by means of the nonrelativistic QED. We verified that the effect of the virtual-photon field increases the squeezing. The relations between the degree of squeezing and the frequency of field, the mean photon number, and the atom-field coupling constant have also been analyzed.
作者机构：
HUA ZHONG NORMAL UNIV,INST PARTICLE PHYS,WUHAN 430070,PEOPLES R CHINA.;TSING HUA UNIV,INST MODERN PHYS,BEIJING 100084,PEOPLES R CHINA.;[SHEN, K] CCAST,WORLD LAB,POB 8730,BEIJING 100080,PEOPLES R CHINA.
通讯机构：
[SHEN, K] C;CCAST,WORLD LAB,POB 8730,BEIJING 100080,PEOPLES R CHINA.
摘要：
Chiral Ward-Takahashi identities with composite fields are generalized to finite temperature and applied to investigate the chiral phase transition and phase structure in the (2 + 1)-dimensional chiral Gross-Neveu model. In terms of these identities, the mass spectra of fermions and bound states and the Goldberger-Treiman relation at finite temperature are obtained. The vertex correction between the fermion and bound states σ is evaluated beyond the leading order in the 1N expansion at zero and finite temperatures. With the aid of the gap equation derived from Ward-Takahashi identities, the phase structure is discussed at zero and finite temperatures. It turns out that (i) at zero temperature, the vertex correction is very small and its influence on the phase structure can be neglected and (ii) at nonzero temperature, the infrared divergence in the vertex correction will make the results of the chiral phase transition obtained at the leading order invalid in next to the leading order and the phase structure is in agreement with Coleman's theorem.
摘要：
The stability of the sonic point in isothermal disc accretion is examined for the case in which the viscous stress has a diffusive form, rather than the form of the conventional Shakura-Sunyaev-type alpha-model. The results show that the sonic point is always a saddle and always stable against small-amplitude perturbations, in contrast to the case of the alpha-model. The results suggest that the topological type of the sonic point and the stability of the point against small-amplitude perturbations are related for a wide range of problems: a saddle-type sonic point is stable, while a nodal one is unstable.
作者机构：
[XU, C] Institute of Particle Physics, Huazhong Normal University, Wuhan 430070, China
通讯机构：
[XU, C] H;HUAZHONG NORMAL UNIV, INST PARTICLE PHYS, WUHAN 430070, PEOPLES R CHINA.
摘要：
In this paper we will describe a new nuclear emulsion technique, a digital controlled method, for making fast and accurate measurement and three-dimensional reconstruction of charged particle tracks in a special nuclear emulsion chamber, which is used as detector with target foil of silver, gold or lead nuclei by the CERN/EMU01 experiment and has the best resolution in the investigation of very high multiplicity in ultra-relativistic heavy ion collisions.
作者机构：
[PENG, JS; LI, GX] HUAZHONG NORMAL UNIV,DEPT PHYS,WUHAN 430070,PEOPLES R CHINA.;[PENG, JS] HARVARD SMITHSONIAN CTR ASTROPHYS,INST THEORET ATOM & MOLEC PHYS,CAMBRIDGE,MA 02138, USA.
通讯机构：
[PENG, JS] H;HARVARD SMITHSONIAN CTR ASTROPHYS,INST THEORET ATOM & MOLEC PHYS,CAMBRIDGE,MA 02138, USA.
摘要：
We investigate the effect of the dipole-dipole interaction on the dynamic properties and the atomic coherent trapping of a two-identical-atom system in the presence of a laser field by means of quantum-electrodynamics theory. The influence of the dipole-dipole interaction on the collapses and revivals of the atomic population is revealed. The conditions of the atomic coherent trapping are given. A way to measure optically the coupling strength between the atoms is pointed out. We also show that the effect of the dipole-dipole interaction may be screened due to the coherent field in certain atomic superposition states.
作者机构：
CHINESE CTR ADV SCI & TECHNOL,WORLD LAB,BEIJING 100080,PEOPLES R CHINA.;HUAZHONG NORMAL UNIV,DEPT PHYS,WUHAN 430070,PEOPLES R CHINA.;UNIV SCI & TECHNOL CHINA,DEPT PHYS,HEFEI 230026,PEOPLES R CHINA.;[YANG, JL] UNIV SCI & TECHNOL CHINA,CTR FUNDAMENTAL PHYS,HEFEI 230026,PEOPLES R CHINA.
通讯机构：
[YANG, JL] U;UNIV SCI & TECHNOL CHINA,CTR FUNDAMENTAL PHYS,HEFEI 230026,PEOPLES R CHINA.
摘要：
The stability, electronic and magnetic properties, and reactivity of icosahedral M Co12 clusters are studied using the discrete variational local-spin-density-functional method, where M=Ti, V, Cr, Mn, Fe, Co, and Ni. By means of the binding-energy calculation, we obtained the M-Co bond length of the clusters and compared their relative stability. We calculated the electronic structure of the clusters in their equilibrium configurations. The calculated results show that all the clusters have metallic character, and that the clusters with M being Ti, Mn, or Co have closed electronic shells while the others have open electronic shells and are expected to distort further. The results also indicate that the cluster moment is reduced by the substitution of the central Co atom with an M atom, and that the average moment per atom of all clusters is larger than that of the bulk Co. Based on the results of electronic structures, we further analyzed the reactivity of the clusters toward H2, N2, and CO molecules and found a strong dependence on the central M atom. Our results compare well with the available experimental results.
作者机构：
ACAD SINICA, INST HIGH ENERGY PHYS, BEIJING 100039, PEOPLES R CHINA.;CCAST, WORLD LAB, BEIJING 100080, PEOPLES R CHINA.;HUA ZHONG NORMAL UNIV, INST PARTICLE PHYS, WUHAN 430070, PEOPLES R CHINA.;[ZHUANG, PF] CCAST (World Laboratory), PO Box 8730, Beijing 100080, China<&wdkj&>Institute of Particle Physics, Hua-Zhong Normal University, Wuhan 430070, China;[CHAO, WQ] CCAST (World Laboratory), PO Box 8730, Beijing 100080, China<&wdkj&>Institute of High Energy Physics, Academia Sinica, Beijing 100039, China
通讯机构：
[Chao Weiqin] C;CCAST (World Laboratory), PO Box 8730, Beijing 100080, China<&wdkj&>Institute of High Energy Physics, Academia Sinica, Beijing 100039, China
摘要：
The relation between the formation time and the intranuclear cascading in high-energy hA collisions is discussed. By comparing the final-state rapidity distribution obtained from a simple model with the experimental data, the appropriate formation time is estimated as about 1 fm.
作者机构：
[WU, YF; LIU, LS] Institute of Particle Physics, Hua-Zhong Normal Univeristy, Wuhan 430 070, People’s Republic of China
通讯机构：
[WU, YF] H;HUA ZHONG NORMAL UNIV,INST PARTICLE PHYS,WUHAN 430070,PEOPLES R CHINA.
摘要：
It is argued that, accounting for the anisotropy of phase space, the local fluctuations of multiplicity in high energy multiparticle production are self-affine rather than self-similar. Evidence is given confirming self-affinity in phase-space distributions. A method is proposed to extract the characteristic parameter of self-affinity, the Hurst exponent, from the experimental data iteratively.
