Superconductivity in Alkali-Doped C60

There ark three kinds of effective attractive interaction between C₆₀^2- and "nearly free" electron in A₃C₆₀: 1) the strong short-range attraction between the low energy unoccupied orbital of C₆₀^2- ions and the "nearly free" electrons; 2) the potential barrier due to large angular momentum of t_1u orbital; 3) the A⁺ crystal field forced "nearly free" electrons in C₆₀^2- neighborhood. All effective attraction coupling with the A⁺ optical modes and the vibration modes of C₆₀ mass center produces a strong electron-phonon interaction. It plays a principal role for A₃C₆₀ superconductivity. Based upon this mechanism critical temperature and other properties of superconductivity state can be explained by means of the BCS theory.     

The Stability of Icosahedral Cluster and the Range of Interaction Potential

The relation between the stability of icosahedral clusters and the range of interaction potential is discussed.We found that the stability of icosahedral clusters nay decrease with decreasing range of interaction potential. A simple formula about the critical number of icosahedral clusters and the range of interaction potential (M1/3c = A1 A2r2eff)was proposed. The calculation of the stability of icosahedral fullerence molecular clusters shows that our idea is right.``     

铜化合物ESR g张量和A张量的相关性及其与结构的关系

对于某些含有特定配位原子的钢化合物,找出了钢的ESR g_‖和A_‖之间的线性相关性;总结了相关性与钢化合物的分子结构间的联系;认为相关性与分子对称性及分子轨道性有关,分子对称性的提高和钢-配体间成键分子轨道共价性的降低引起g_‖的增大和A_‖绝对值的减小,对某些钢化合物,g_‖与β₁²,A_‖与β₁²之间存在线性关系.总结出由实测的g_‖和A_‖估算分子轨道系数β₁²值的方法.     

13Cu、65Cu和15N标记的二(2-羟基苯乙酮肟)-铜(Ⅱ)配合物的ESR波谱研究

本文解析了同位素标记的⁶³Cu-¹⁴N-HAP,⁶⁵Cu-¹⁴N-HAP,⁶³Cu-¹⁵N-HAP。⁶⁵Cu-¹⁵N-HAP,和Cu-¹⁵N-HAP,等五种配合物在四氢呋喃中,在77K温度下测得的分辨较好的ESR波谱。从图上不仅得到了⁶³Cu和⁶³Cu的超精细分裂,而且还得出分辨较好的¹⁴N和¹⁵N的超超精细分裂。比较合理地确定了g_x,g_y,g_z;A_x⁶⁵,A_y⁶⁵,A_z⁶⁵和A_x⁶³,A_y⁶³,A_z⁶³以及A_⊥¹⁵,A_⊥¹⁵和A_⊥¹⁴,A_⊥¹⁴等张量参数。利用测得的波谱参数计算了键参数,并讨论了配合物的电子结构及成键特性,得到了较满意的结果。     

Boundary A1(1) Face Model

In this paper, we study the boundary state and its dual state in A₁⁽¹⁾ face model with a fixed boundary weight condition, which corresponds to the diagonal solution to boundary Yang-Baxter equation in face model. We also give the correlation functions in this boundary A₁⁽¹⁾ face model.     

Study on the Effects of the Light CP-odd Higgs via the Leptonic Decays of Pseudoscalar Mesons

To explain the anomalously large decay rate of Σ⁺→p+μ⁺μ^-, it was proposed that a new mechanism where a light CP-odd pseudoscalar boson of m_A1⁰=214.3 MeV makes a crucial contribution. Later, some authors have studied the transition π⁰→ e⁺e^- and r → γA₁⁰ in terms of the same mechanism and their result indicates that with the suggested mass one cannot fit the data. This discrepancy might be caused by experimental error of Σ⁺→ p+μ⁺μ^- because there were only a few events. Whether the mechanism is a reasonable one motivates us to investigate the transitions π⁰→ e⁺e^-;η(η')→ μ⁺μ^-; η_c→ μ⁺μ^-; η_b→τ⁺τ^- within the same framework. It is noted that for π⁰→ e⁺e^-, the standard model (SM) prediction is smaller than the data, whereas the experimental central value of η→μ⁺μ^- is also above the SM prediction. It means that there should be extra contributions from other mechanisms and the contribution of A₁⁰ may be a possible one. Theoretically calculating the branching ratios of the concerned modes, we would check if we can obtain a universal mass for A₁⁰ which reconcile the theoretical predictions and data for all the modes. Unfortunately, we find that it is impossible to have such a mass with the same coupling |gl|. Therefore we conclude that the phenomenology does not favor such a light A₁⁰, even though a small window is still open.     

Formation Mechanism and Binding Energy for Icosahedral Central Structure of He13^＋ Cluster

The formation mechanism for the icosahedral central structure of the He13^ cluster is proposed and its total energy curve is calculated by the method of a Modified Arrangement Channel Quantum Mechanics. The energy is the function of separation R between two nuclei at the center and an apex of the icosahedral central structure. The result of the calculation has shown that the curve has a minimal energy -37.5765 (a.u.) at R=2.70ao. The binding energy of He13^ with respect to He^ 12He was calculated to be 1.4046 a.u. This means that the cluster of He13^ may be formed in an icosahedral central structure with strong binding energy.     

五种还原Keggin结构杂多阴离子的ESR谱

本文报道了五种具有Keggin结构的还原杂多阴离子的溶液和-150℃冷冻ESR谱,它们是SiV₂Mo₁₀O₄₀^6-、bSiV₂Mo₉O₄₀^7--、PV₃Mo₉O₄₀^6-、PV₃W₉O₄₀^6-和VV₃W₉O₄₀^6-。在室温下pH≤3时,所有杂多酸阴离子均为8条锐线,pH=7-8时,均为8+15条线并且随着放置时间增长逐步变成8条线。在-150℃时均呈现出V⁴⁺8条线的复杂粉末谱,作者根据一种修正的Ble-aney方法成功地模拟了这些冷冻谱,得出g_‖、g_⊥、A_‖、A_⊥,按照DeArmond理论计算了近似的K、α值并讨论了它们的物理意义。最后从异构体的数目和简并度的观点初步解释了观察不到V₃物种22条超精细线的原因。Back     

Theoretical Calculations of Strain—Induced Splittings and／or Shifts of t2^32E and t2^34A2 Levels for MgO：Cr^3＋

Under various uniaxial stresses, both strains with low symmetry and isotropic strains of crystals take place. The former gives the strain-induced low-symmetry crystal fields and accordingly splittings of levels; the latter gives the isotropic parts of strain-induced crystal fields and accordingly shifts of levels. By using the wavefunctions obtained from the diagonalization of the complete d^3$ energy matrix in a regular octahedral field, the relevant matrix elements and accordingly strain-induced splittings and/or shifts of t₂³²E and t₂³⁴A₂ for MgO:Cr³⁺ have been calculated. Their physical origins have been thoroughly analyzed and revealed. It is the admixtures of basic wavefunctions resulted from the spin-orbit interaction and/or Coulomb interaction and/or Kramers degeneracy that make strain-induced splittings of levels nonzero. In contrast with this, strain-induced shifts come mainly from the zero-order approximate wavefunctions. It is found that there are nonvanishing matrix elements of operators T₂ξ, T₂η and T₂ζ between wavefunctions with positive M_s and those with negative M_s', which have important effects on strain-induced splittings of levels. The shifts of t₂³²E under both hydrostatic pressure and uniaxial pressure have been uniformly calculated. The important results of Y_c, Z_c, P_c, Q_c and 〈t₂|| C(A₁)|| t₂〉have been evaluated.     

Theoretical Study on the Low-Lying Electronic States of He2, He2+, and He2++

The equilibrium geometries, potential energy curves, spectroscopic dissociation energies of the ground and low-lying electronic states of He₂, He₂⁺ and He₂⁺⁺ are calculated using symmetry adapted cluster/symmetry adapted cluster-configuration interaction (SAC/SAC-CI) method with the basis sets CC-PV5Z. The corresponding dissociation limits for all states are derived based on atomic and molecular reaction statics. The analytical potential energy functions of these states are fitted with Murrell--Sorbie potential energy function from our calculation results. The spectroscopic constants B_e, α _e, ω _e, and ω _e χ _e of these states are calculated through the relationship between spectroscopic data and analytical energy function, which are in well agreement with the experimental data. In addition, the origin of the energy barrier in the ground state X¹Σ_g⁺ of He₂⁺⁺ energy curve are explained using the avoided crossing rules of valence bond model.     

Pressure-Dependent Base-Wavefunction Admixture and Lifetime of R1 State of La3Lu2Ga3O12:Cr3+

As a key factor leading to the pressure-dependent R₁-line-shift reversal and R₁-state lifetime, at 10 K, the pressure-dependent variation of mixing-degree of |t₂²(³T₁)e⁴T₂〉 and |t₂³² E〉base-wavefunctions in the wavefunction of R₁ state of LLGG:Cr³⁺ has been calculated and analyzed. From this, the physical origin of the pressure-dependent R₁-line-shift reversal has been revealed. Furthermore, by using the pressure-dependent values of the sum of all square mixing-coefficients of |t₂²(³T₁)e⁴T₂〉in the wavefunction of R₁ state, the lifetimes of R₁ state of LLGG:Cr³⁺ at various pressures have been calculated, which are in good agreement with observed results. The quantum anticrossing effect between t₂³²E and t₂²(³T₁)e⁴T₂ levels due to both spin-orbital interaction and electron-phonon interaction is remarkable, which is related to the admixture of |t₂²(³T₁)e⁴T₂〉and |t₂³² E〉as well as the low-high crystal-field transition.     

Energy Spectrum,g Factors,Strain-Induced Level-Splittingsand R-Line Thermal Shift of MgO:V2+

Traditional ligand-field theory has to be improved by taking into account both pure electronic contribution and electron-phonon interaction one (including lattice-vibrational relaxation energy). By means of improved ligand-field theory, the R line, t₂^{3 2}T₁ and t₂^{3 2}T₂ lines, t₂² (³T₁)e⁴T₂, t₂² (³T₁)e⁴T₁ and t₂ e²(⁴A₂)⁴T₁ bands, g factors of t₂^{3 4}A₂ and t₂^{3 2}E, four strain-induced level-splittings and R-line thermal shift of MgO:V₂₊ have been calculated. The results are in very good agreement with the experimental data. It is found that for MgO:V₂₊, the contributions due to electron-phonon interaction (EPI) come from the first-order term; the contributions from the second-order and higher terms are insignificant. In thermal shift of R line of MgO:V₂₊, the temperature-dependent contribution due to EPI is dominant. The results obtained in this work may be used in theoretical calculations of other effects of EPI.     

Na_2~+离子较低电子态势能曲线和光谱常数的理论研究

通过多组态相互作用方法,结合原子有效芯势与极化势,利用非收缩的高斯基函数,计算了Na_2~+分子对应最低9个解离限的36个电子态的势能曲线.基于计算获得的束缚态势能曲线,拟合给出了相应的光谱常数,并与已有的实验和理论结果进行了比较.同时,给出了部分电子态的振动-转动能级和一些同类态避免交叉点的信息.计算获得的光谱信息对冷原子分子光谱与动力学的研究具有参考价值.     

超冷铯分子0u+(6P3/2)长程态的高灵敏光缔合光谱研究

利用发展的调制俘获损耗荧光光谱技术实验测量了超冷铯分子0_u⁺(6P_3/2)长程态的高灵敏光缔合光谱. 光谱探测范围较国际已有报道扩大了60 cm^-1, 观察到25个长程区域新的振动能级. 通过LeRoy-Bernstein公式对振动束缚能数据进行拟合, 获得了超冷铯分子0_u⁺(6P_3/2)态的长程系数C₃ 为16.103±0.010. 构建了超冷铯分子0_u⁺(6P_3/2)态长程区域的势能曲线.     

AlH~+离子5个Λ-S态和10个?态的光谱性质以及激光冷却的理论研究

利用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV6Z计算了AlH~+离子前两个离解极限对应的5个Λ-S态和10个?态的势能曲线.为了提高势能曲线的可靠性和精确性,计算中考虑了自旋轨道耦合效应、芯电子价电子相关和标量相对论修正以及将势能外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的4个Λ-S态和8个?态的光谱常数和振动能级,与已有的实验结果符合.计算了2(1/2)→X~2Σ_(1/2)~+和A~2Π_(3/2)→X~2Σ_(1/2)~+跃迁的跃迁偶极距.利用计算的精确的势能曲线和跃迁偶极矩,获得了2(1/2)~(第一势阱)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)和A~2Π_(3/2)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)跃迁的高度对角化分布的Franck-Condon因子(f_(00)和f_(11))和大的振动分支比;预测了2(1/2)~(第一势阱)(υ′=0, 1)和A~2Π_(3/2)(υ′=0, 1)态短的自发辐射寿命和窄的辐射宽度,这适合于AlH~+离子的快速激光致冷.所需的3束激光冷却波长都在紫外区域.这些结果表明了激光冷却AlH~+离子的可行性.此外,评估了自旋轨道耦合效应对光谱常数、振动能级和激光冷却AlH~+离子的影响.     

Collisional Quantum Interference on Rotational Energy Transfer： Relation Between Integral Interference Angle and Rotational Quantum Number in Na2（A^1∑u^＋,ν=8～b^3∏0u,ν=14）-Na System

Collisional quantum interference （CQI） on rotational energy transfer was observed in Na2（A^1∑u^＋,ν=8～b^3∏0u,ν=14） system in collision with Na [Chem. Phys. Lett. 318 （2000） 107], and the degree of the interference was measured. The integral interference angle was obtaJned through theoretical calculation. We will research the factors that have effect on collisional quantum interference on rotational energy transfer in Na2（A^1∑u^＋,ν=8～b^3∏0u,ν=14）-Na system. Basing on the time-dependent first order Born approximation, and taking into account the anlsotroplc Lennard Jones interaction potentials and ＂straight-line＂ trajectory approximation, we obtain the factors that have effect on CQI in Na2-Na system, and obtain the relation between the integral interference angle and rotational quantum number.     

Theoretical study of spin-forbidden cooling transitions of indium hydride using ab initio methods

The feasibility of spin-forbidden cooling of the In H molecule is investigated based on ab initio quantum chemistry calculations. The potential energy curves for the X~1Σ_(0~+)~+, a~3Π_~(0~-), a~3Π_(0~+), a~3Π_1, a~3Π_2, A~1Π_1, 1~3Σ_(0~-)~+, and 1~3Σ_1~+states of In H are obtained based on multi-reference configuration interaction plus the Davidson corrections method. The calculated spectroscopic constants are in good agreement with the available experimental data. In addition, the influences of the active space and spin–orbit coupling effects on the potential energy curves and spectroscopic constants are also studied. For Re of a~3Π_(0~-), a~3Π_(0~+), a~3Π_1, and a~3Π_2 states, the error from large active space is small. The potential energy curve of the A~1Π_1state is not smooth for small active space. The spin–orbit coupling effects have great influences on the potential well depth and equilibrium internuclear distance of the A~1Π state. The Franck–Condon factors and radiative lifetimes are obtained on the basis of the transition dipole moments of the a~3Π_(0~+) → X~1Σ_(0~+)~+, a~3Π_1 → X~1Σ_(0~+)~+, and A~1Π_1 → X~1Σ_(0~+)~+ transitions. Our calculation indicates that the a~3Π_1( ν'= 0) → X~1Σ_(0~+)~+(ν = 0) transition provides a highly diagonally distributed Franck–Condon factor and a short radiative lifetime for the a3Π1 state, which can ensure rapid and efficient laser cooling of In H.The proposed laser drives a~3Π_1 → X~1Σ_(0~+)~+ transitions by using three wavelengths.     

Energy Spectrum and Its Pressure-Induced Shift and J-T Effect of ZnTe:Mn2+

By using strong-field scheme, the complete d⁵ energy matrix with symmetry has been constructed. Then, by diagonalization of this matrix at normal and various pressures,the whole energy spectrum [including the ground-state zero-field splitting (GSZFS)] and its pressure-induced shift (PS) of Znlb:Mn²⁺ have uniformly been calculated. The results are in very good agreement with experimental data. According to the eigenfimctions and PS, the assignments of four absorption bands have been given. By taking into account the dect of different deformations of t₂ and e radial wavefunctions on t₂³(⁴A₂)e²(³A₂)⁴ A₁ and t₂³(²E)e²(³A₂)⁴E, the position of the third absorption band at normal pressure has been estimated.The tetragonal field is important for GSZFS of ZnTe:Mn²⁺ and its PS, which supports the existence of tetragonal Jahn-Teller distortion in ZnTe:Mn²⁺ The physical essentials of typical levels, GSZFS and their PS have been revealed.     

原子间(锂-锂,氟-氟)位能曲线的ab initio计算

使用先进的量子化学ab initio程序MONSTERGAUSS和各种基函数组,在较大的核间距内计算了锂-锂,氟-氟原子间的位能曲线。并采用组态相互作用(CI)方法计算了基态锂分子(Li₂ ¹∑_g⁺)和基态氟分子(F₂ ¹∑_g⁺)的平衡核间距及总能量。计算结果与其它理论和实验结果进行了比较。     

NH4H2PO4和ND4D2PO4晶体微结构的拉曼光谱研究

本文利用偏振拉曼光谱和第一性原理, 对磷酸二氢铵(NH₄H₂PO₄, ADP)和不同氘含量磷酸二氢铵DADP晶体的晶格振动模式进行了研究. 实验测得了不同几何配置、200–4000 cm^-1范围的偏振拉曼光谱, 分析在不同氘含量条件下921 cm^-1和3000 cm^-1附近拉曼峰的变化. 在ADP晶体中, 基于基本结构单元NH₄⁺ 和H₂PO₄^-基团的振动模, 用第一性原理进行了数值模拟, 进一步明确拉曼峰与晶体中原子振动的对应关系; 通过洛伦兹拟合不同氘含量DADP晶体的拉曼光谱中2000–2600 cm^-1处各峰的变化讨论了DADP 晶体的氘化过程, 结果表明氘化顺序是先NH₄⁺ 基团后H₂PO₄^-基团, 研究结果为今后此类材料的生长和性能优化奠定了基础.