Potential energy curves and analytical potential energy functions of the metastable states of B2^＋＋

The multi-reference configuration interaction method and aug-cc-pvqz （AVQZ） have been used to calculate potential energy curves （PECs） of the singlet and triplet states of the riu and rig symmetry of B2＋＋. All of the four states （^l∏u, ^1∏g, ^3∏u and ^3∏g） are found to be metastable states, though the potential well of ^3∏u symmetry is very shallow. Based on the PECs, the analytical potential energy functions （APEFs） of these states have been fitted using the least square fitting method and two models of function. The spectroscopic parameters of each state are also calculated, and are compared with other investigations in the literature. The credibility and veracity of the two functions are evaluated. Some ideas to improve the fitting accuracy are presented. Also the vibrational levels for each state are predicted by solving the SchrSdinger equation of nuclear motion.     

Accurate calculation of the elastic scattering properties of ^7Li atoms at ultralow temperatures

The elastic scattering properties for collisions between two ^7Li atoms are investigated in the cold and ultracold regimes separately. Based on recent theoretical and experimental results, we present the improved hybrid potentials for the singlet X^1 ∑g^＋ and triplet a^3 ∑u^＋ ground states of the Li2, Our calculated values for the scattering lengths α and the effective ranges re are compared with previous ones, and found them to be in good agreement. The scattering lengths are 34.6α0 for the singlet state and -27.6α0 for the triplet state. Shape resonances occur in the collisions at low energies. We also calculate the total cross sections and the energy positions of shape resonances for both X^1 ∑g^＋ and a^3 ∑u^＋ states.     

Collision of Bare Ion Si~(14+) with the Same Z Slow-atom Si

We present the collision of bare ion Si 14+ with the same Z slow atom Si. It is shown that the cold-atom collisions are sensitive to the potential. In this paper, we present the cross sectiond for the most important transition from the 3p 13d 1 and 3p 14d 1 excited states. It is seen that there are large cross sections when the angle is larger than 80 degrees. With increasing energy, the cross section becomes decresasingly flat. PACS numbers: 34.70.+e, 32.80. Fb     

Electron Capture Process in Collisions of Proton with Excited State of Helium

Total and star,selective cross sections for single electron capture （SEC） from the n = 2 excited state of helium colliding by protons are calculated in the energy range of 1.0-100.0 ke V/u by using the two-center atomic orbital close-coupling method. The interaction of the active electron with helium ion is represented by a model potential. Total SEC cross sections show a monotonic decreasing trend with increasing collision energy, and display a different behavior compared with the case from the ground state of helium. It is also found that the dominant reaction channel is captured to the H（2p） state up to 40 keV//u, and then the capture to the H（1s） or H（2s） state becomes more pronounced. Moreover, the alignment dependence on the initial states is obtained for the electron capture from He（2p0） and He （2p1）.     

Theoretical Study of Isotopic Effect of Oxygen Atom on the Stereodynamics for the O（^3P） ＋ D2 → OD ＋ D Reaction

Quasi-classical trajectory theory is used to study the isotope effect of oxygen atoms on the vector correlations in the O（^3P） ＋ D reaction at a collision energy of 25kcal/mol using accurate potential energy surface of the 3A＇ triplet state. The distributions of p（θr） and the distribution of dihedral angel p（φr） as well as p（θr,φr） are calculated. Moreover, four polarization-dependent generalized differential cross sections （PDDCSs） of product are presented in the center-of-mass frame. The results indicate that the polarization of the product presents different characters for the isotope effect of oxygen atoms. Isotopic substitute can cause obviously different effects on the four PDDCSs.     

Resonant charge transfer in slow Li~+–Li(2s) collision

The resonant charge transfer process for Li+–Li(2s) collision is investigated by the quantum-mechanical molecular orbital close-coupling(QMOCC) method and the two-center atomic-orbital close-coupling(AOCC) method in an energy range of 1.0 e V/u–104e V/u. Accurate molecular structure data and charge transfer cross sections are given. Both the allelectron model(AEM) and one-electron model(OEM) are used in the QMOCC calculations, and the discrepancies between the two models are analyzed. The OEM calculation can also give a reliable prediction of the cross sections for energies below 1 ke V/u.     

Study of the H＋HS reaction on a newly built potential energy surface using the quasi-classical trajectory method

<正>The quasi-classical trajectory（QCT） method is used to study the H+HS reaction on a newly built potential energy surface（PES） of the triplet state of H₂S（³A″） in a collision energy range of 0-60 kcal/mol.Both scalar properties, such as the reaction probability and the integral cross section（ICS）,and the vector properties,such as the angular distribution between the relative velocity vector of the reactant and that of the product,etc.,are investigated using the QCT method.It is found that the ICSs obtained by the QCT method and the quantum mechanical（QM） method accord well with each other.In addition,the distribution for the product vibrational states is cold,while that for the product rotational states is hot for both reaction channels in the whole energy range studied here.     

Calculation of Elastic Scattering Properties in an Ultra-Cold ^85Rb-^85Rb Vapour

We report the calculation of the same-species elastic scattering properties for the ultracold rubidium-rubidium (^85Rb-^85Rb) system and the results are compared with other theoretical and experimental results in detail. We present an improved potential for triplet ground states of the Rb2 molecule, and calculate the scattering lengths αt and the effective range re using WKB and Numerov methods for two rubidium-85 collisions in the triplet state. Also, we investigate the convergence of these scattering properties, i.e. the dependence on core radius and K^0 parameter using quantum defect theory and the analytic calculations of scattering length obtained by Szmytkowski. In addition, we present evaporative cooling and other results that include phase shift and cross section at zero energy limit.     

Multi-Electron Processes in 4.15-11.08 keV/u^13C^6＋ on Argon Collisions

The relative partial cross sections for ^13C^6＋ -Ar collisions at 4.15-11.08 ke V/u incident energy are measured. The cross-section ratios σ^2E/σ^SC, σ^3E/σ^SC, σ^4E/σ^SC and σ^SE/σ^SC are approximately the constants of 0.514-0.05, 0.204-0.03, 0.064-0.03 and 0.024-0.01 in this region. The significance of the multi-electron process in highly charged ions （HCIs） with argon collisions is demonstrated （σ^ME/σ^SC as high as 0.794-0.06）. In multi-electron processes, it is shown that transfer ionization is dominant while pure electron capture is weak and negligible. For all reaction channels, the cross-sections are independent of the incident energy in the present energy region, which is in agreement with the static characteristic of classic models, i.e. the molecular Coulomb over-the-barrier model （MCBM）, the extended classical over-the-barrier model （ECBM） and the semiempirical scaling laws （SL）. The result is compared with these classical models and with our previous work of ^13C^6＋ -Ne collisions [Chin. Phys. Lett. 23 （2006） 95].     

Variation of Ionization Mechanisms with q in the Collision of He^2＋ with C^q＋

The ionization process in the collisions of He^2＋ with C^q＋ （q = 0-5） is investigated by using the continuum-distorted-wave eikonal-initial-state approximation. Double-differential cross sections for 1s and 2s sub-shells are obtained at the electron-ejected angle θ = 0° with the projectile energy ranging from 30keV/u to 10MeV/u. Variation of ionization mechanisms with q in C^q＋ is studied, and the dependences on the projectile energies and target sub-shells are also discussed. It is found that in the whole energy range, the absolute values of soft collision （SC） and binary encounter （BE） peaks decrease with increasing q. For the lower incident energies, the electron capture to the projectile continuum （ECC） peak decrease with increasing q as well as SC and BE peaks. For the higher incident energies （〉 1 MeV/u）, the absolute value of ECC peak increases with increasing q, so that the crossings of cross sections appear for C^q＋ with different q. This can be explained by the matching of velocities between the projectile and the electron initially bound to the target.     

Electrical and deep levels characteristics of ZnO/Si heterostructure by MOCVD deposition

ZnO films have been prepared on p-type Si substrates by metal-organic chemical vapour deposition （MOCVD） at different total gas flow rates. The current versus voltage and temperature （I - V - T） characteristics, the deep-level transient spectroscopy （DLTS） and the photoluminescence （PL） spectra of the samples were measured. DLTS shows two deep-level centres of E1 （Ec-0.13±0.02eV） and E2 （Ec-0.43±0.05eV） in sample 1202a, which has a ZnO/p-Si heterostructure. A deep level at Ec-0.13±0.01 eV was also obtained from the I -T characteristics. It was considered to be the same as E1 obtained from DLTS measurement. The emission related to this deep level center was detected by PL spectra. In addition, the energy location and the relative trap density of E1 was varied when the total gas flow rate was changed.     

Elastic scattering of two H（^2Sg） and N（^4Su） atoms at low temperatures and accurate spectroscopic parameters of NH （X^3∑^-） radical

This paper reports that the interaction potential for the X3Z- state of NH radical is constructed at the CCSD（T）/ cc-PV6Z level of theory. Using this potential, this paper calculates the spectroscopic parameters （De, Re, ωe, ωeχe, αe and Be） and their values are of 3.578eV, 0.10368nm, 3286.833cm^-1, 78.433cm^-1, 0.6469cm^-1 and 16.6735cm^-1 respectively, which are in excellent agreement with the experiments. Then the total of 14 vibrational states has been found when J=0 by solving the radial Schrodinger equation of nuclear motion. For each vibrational state, the vibrational manifolds are reported for the first time. And last, the total cross sections, s-wave, p-wave and d-wave cross sections are computed for the elastic collisions between two ground-state atoms （hydrogen and nitrogen） at low temperatures. It finds that the total elastic cross sections are dominated by s-wave scattering when the collision energy is below 10^-6a.u. The pronounced shape resonance is found at energy of 6.1 × 10^-6a.u. Calculations have shown that the shape resonance comes from the p-wave contributions.     

Elastic collisions of sulfur and hydrogen in their ground states at low temperatures and spectroscopic parameters of SH（X^2∏） radical

This paper constructs the interaction potential of the SH（X^2∏） radical by using the coupled-cluster singlesdoubles-approximate-triples theory combining the correlation-consistent quintuple basis set augmented with the diffuse functions, aug-cc-pV5Z, in the valence range. Employing the potential, it accurately determines the spectroscopic parameters. The present De, Re, ωe, ωeχe, ae and Be values are of 3.7767eV, 0.13424nm, 2699.846 cm^-1, 47.7055 cm^-1, 0.2639cm^-1 and 9.4414 cm^-1, respectively, which are in excellent agreement with those obtained from the measure- ments. A total of 19 vibrational states has been found when J = 0 by solving the radial SchrSdinger equation of nuclear motion. The complete vibrational levels, classical turning points, initial rotation and centrifugal distortion constants when J = 0 are reported for the first time, which are in good accord with the experimental results. The total and various partial-wave cross sections are computed for the elastic collisions of sulfur and hydrogen in their ground states at low temperatures when two atoms approach each other along the SH（X^2∏） potential energy curve. Over the impact energy range from 1.0×10^-11 to 1.0×10^-4 a.u., eight shape resonances have been found in the total elastic cross sections. For each shape resonance, the resonant energy is accurately calculated. Careful investigations have pointed out that these resonances result from the 1 = 0, 1, 2, 3, 4, 6, 7, 8 partial-wave contributions.     

Spin polarization effect for Cr2 molecule

Density functional theory （DFT） （B3P86） of Gaussian 03 has been used to optimize the structure of the Cr2 molecule, a transition metal element molecule. The result shows that the ground state for the Cr2 molecule is a 13- multiple state, indicating that there exists a spin polarization effect in the Cr2 molecule. Meanwhile, we have not found any spin pollution because the wave function of the ground state does not mingle with wave functions of higher-energy states. So the ground state for Cr2 molecule being a 13-multiple state is indicative of spin polarization effect of the Cr2 molecule among transition metal elements, that is, there are 12 parallel spin electrons in the Cr2 molecule. The number of non-conjugated electrons is greatest. These electrons occupy different spatial orbitals so that the energy of the Cr2 molecule is minimized. It can be concluded that the effect of parallel spin in the Cr2 molecule is larger than the effect of the conjugated molecule, which is obviously related to the effect of electron d delocalization. In addition, the Murrell Sorbie potential functions with the parameters for the ground state and other states of the Cr2 molecule are derived. The dissociation energy De for the ground state of the Cr2 molecule is 0.1034eV, equilibrium bond length Re is 0.3396 nm, and vibration frequency we is 73.81cm^-1. Its force constants f2, f3 and f4 are 0.0835, -0.2831 and 0.3535 aJ. nm^-4 respectively. The other spectroscopic data for the ground state of the Cr2 molecule ωeχe, Be and αe are 1.2105, 0.0562 and 7.2938 x 10^-4cm^-1 respectively.     

Synthesis and characterization of Ca2Sn1-xCexO4 with blue luminescence originating from Ce^4＋ charge transfer transition

Ce^4＋-doped Ca2SnO4 with a one-dimensional structure, which emits bright blue light, is prepared by using a solid-state reaction method. The x-ray diffraction results show that the Ce^4＋ ions doped in Ca2SnO4 occupy the Sn^4＋ sites. The excitation and emission spectra of Ca2Sn1-xCexO4 appear to have broad bands with peaks at - 268nm and -442nm, respectively. A long excited-state lifetime （-83μs） for the emission from Ca2Sn1-xCexO4 suggests that the luminescence originates from a ligand-to-metal Ce^4＋ charge transfer （CT）. The luminescent properties of Ca2Snl_xCexO4 have been compared with those of Sr2CeO4, which is the only material reported so far to show Ce^4＋ CT luminescence. More interestingly, it is observed that the emission intensity of Ca2Sn1-xCexO4 with a small doping concentration （x - 0.03） is comparable to that of Sr2CeO4 in which the concentration of active centre is 100%.     

Ab initio calculations on the α^3∑u^＋ state properties of dimer ^7Li2

The comparison between single-point energy scanning （SPES） and geometry optimization （OPT） in determining the equilibrium geometry of the α^3∑u^＋ state for ^7Li2 is made at numerous basis sets such as 6-311＋＋G（2df）, cc-PVTZ, 6-311＋＋G（2df, p）, 6-311G（3df,3pd）, 6-311＋＋G（2df,2pd）, D95（3df,3pd）, 6-311＋＋G, DGDZVP, 6-311＋＋G（3df,2pd）, 6-311G（2df,2pd）, D95V＋＋, CEP-121G, 6-311＋＋G（d,p）, 6-311＋＋G（2df, pd） and 6-311＋＋G（3df,3pd） in full active space using a symmetry-adapted-cluster/ symmetry-adapted-cluster configuration-interaction （SAC/SAC=CI） method presented in Gaussian03 program package. The difference of the equilibrium geometries obtained by SPES and by OPT is reported. Analyses show that the results obtained by SPES are more reasonable than those obtained by OPT. We have calculated the complete potential energy curves at those sets over a wide internuclear distance range from about 3.0α0 to 37.0α0, and the conclusion is that the basis set cc-PVTZ is the most suitable one. With the potential obtained at ccopVTZ, the spectroscopic data （Te, De, D0, ωe,ωeХe, αe and Be） are computed and they are 1.006 eV, 338.71 cm^-1, 307.12 cm^-1, 64.88 cm^-1, 3.41 cm^-1, 0.0187 cm^-1 and 0.279 cm^-1, respectively, which are in good agreement with recent measurements. The total 11 vibrational states are found at J=0. Their corresponding vibrational levels and classical turning points are computed and compared with available RKR data, and good agreement is found. One inertial rotation constant （By） and six centrifugal distortion constants （Dr Hv, Lv, My, Nv, and Ov） are calculated. The scattering length is calculated to be -27.138α0, which is in good accord with the experimental data.     

Electron tunnelling phase time and dwell time through an associated delta potential barrier

The electron tunnelling phase time τP and dwell time τD through an associated delta potential barrier U(x) = ξδ(x) are calculated and both are in the order of 10^-17～10^-16s. The results show that the dependence of the phase time on the delta barrier parameter ξ can be described by the characteristic length lc = h^2/meξ and the characteristic energy Ec=meξ^2/h^2 of the delta barrier, where me is the electron mass, lc and Ec are assumed to be the effective width and height of the delta barrier with lcEc=ξ, respectively. It is found that TD reaches its maximum and τD = τp as the energy of the tunnelling electron is equal to Ec/2, i.e. as lc =λDB, λDB is de Broglie wave length of the electron.     

Isotopic effect of Cl2+ rovibronic spectra in the A-X system

This paper studies the isotopic effect of Cl2+ rovibronic spectra in the A2Πu(Ω=1/2) X 2Πg(Ω= 1/2) system.Based on the experimental results of the molecular constants of 35 Cl2+,it calculates the vibrational isotope shifts of the(2,7) and(3,7) band between the isotopic species 35 Cl+2,35 Cl 37 Cl+and 37 Cl2+,and estimates the rotational constants of both A 2 Π u and X 2 Π g states for the minor isotopic species 35 Cl 37 Cl+and 37 Cl2+.The experimental results of the spectrum of 35 Cl 37 Cl+(3,7) band proves the above mentioned theoretical calculation.The molecular constants and thus resultant rovibronic spectrum for 37 Cl2+ were predicted,which will be helpful for further experimental investigation.     

Kiselev黑洞的热力学性质和物质吸积特性

本文考虑带有黑洞视界和宇宙视界的Kiselev时空.研究以黑洞视界和宇宙视界为边界的系统的热力学性质.统一地给出了两个系统的热力学第一定律;在黑洞视界半径远小于宇宙视界半径的情况下,近似地计算了通过宇宙视界和黑洞视界的热能.然后,探讨Kiselev时空的物质吸积特性.在吸积能量密度正比于背景能量密度的条件下给出黑洞的吸积率,讨论了黑洞吸积率与暗能量态方程参数的关系.