碱金属Li,Na,K,Rb,Cs,Fr的ns2S1/2,np2P1/2,3/2, nd2D3/2,5/2 和nf2F5/2,7/2 里德伯能级理论研究

本文在多通道量子数亏损理论(MQDT)框架下,利用相对论多通道理论(RMCT),分别在冻结实近似、 考虑Δl=-1的偶极极化效应、Δl=+1的偶极极化效应、Δl=± 1的偶极极化效应、伸缩模效应以及同时考虑偶极极化效应和伸缩模效应等不同层次近似下,系统地计算了碱金属Li, Na, K, Rb, Cs和Fr七个里德伯系列的能级,即ns²S_1/2, np²P_1/2, np²P_3/2, nd²D_3/2, nd²D_5/2, nf²F_5/2 和nf²F_7/2.计算结果表明,电子关联效应对碱金属原子的里德伯能级的影响很大.总的来说,偶极极化效应比伸缩模效应重要,而在偶极极化效应中, Δl = + 1的偶极极化效应比Δl = - 1的偶极极化效应重要.但对于Na的ns²S_1/2,(nd²D_3/2,nd²D_5/2)里德伯系列的能级,和Li的(np²P_1/2,np²P_3/2)里德伯系列的能级,是伸缩模效应比较重要.     

7Li2(X1Σ+g)分子的振动能级、转动惯量及离心畸变常数

使用密度泛函理论B3LYP和B3P86，以及组态相互作用方法CCSD(T)和QCISD, 利用多个基组对⁷Li₂(X¹Σ⁺_g)分子的平衡核间距(R_e)、谐振频率(ω_e)和离解能(D_e)进行了计算, 发现在CCSD(T)/cc-PVQZ理论水平下得到的结果(R_{e相似文献}   

PH, PD和PT分子常数理论研究

采用内收缩多参考组态相互作用(MRCI)方法和包含Davidson修正(+Q) 的MRCI方法结合相关一致基aug-cc-pV5Z研究了PH (X³Σ^-, a¹Δ和A³∏)分子的势能曲线. 在同位素质量识别的基础上对势能曲线进行拟合, 得到PH, PD和PT分子各个电子态的光谱常数(T_e, R_e, ω_e, ω_ex_e, α_e和 B_e). 通过与已有实验数据的比较发现, 本文的结果与实验结果非常一致. 对于PH, PD和PT分子的Σ^-电子态, 计算得到了J = 0时的前12个振动态. 对于每一个振动态, 还分别计算了它的振动能级、惯性转动常数和离心畸变常数. 与其他理论结果和实验数据进行比较可知, 本文的结果更精确、更完整. 文中PD和PT分子的光谱常数和分子常数均属首次报导.     

高分辨的一氧化二氮光解离实验研究

利用"时间切片"离子速度成像技术研究了N₂O分子在134.20、135.20和136.43 nm波长下的真空紫外光解动力学. 实验中通过采集解离产物O(¹S_J=0)的离子影像来研究O(¹S_J=0)+N₂(X¹∑_g⁺)这一解离通道. 从各个波长下的实验影像可获得产物N₂(X¹∑_g⁺)的振动态分辨的结构,进而得到产物的总平动能谱和产物N₂的振动态布居. 实验结果表明在实验的光解波长下,产物N₂(X¹∑_g⁺)主要布居在v=2和v=3. 此外,还得到了产物N₂的振动态分辨的各向异性参数β,从中发现产物N₂的β值在三个解离波长下均表现出相似的特征,即随着振动量子数的增大,β值从趋近于2逐渐减小至1.4. 这一现象表明低振动态产物是通过一个以平行跃迁解离为主的解离过程产生的,而高振动态的产物来自于一个更加弯曲的中间构型的解离. 此推论与在平动能谱中所见到的最强转动态布居随着振动量子数的增大而出现的位移是相一致的.     

Electronic structures and magnetoelectric properties of tetragonal BaFeO3: an ab initio density functional theory study

First-principles calculations have been performed to investigate the ground state electronic properties of BaFeO₃ (BFO). Local spin density approximation (LSDA) plus U (LSDA+U) treatment modified the metallic behaviour to insulated one with a band gap of 4.12eV. The spontaneous polarization was found to be 89.3\muC/cm² with Berry phase scheme in terms of the modern theory of polarization. Fe-3d e_g were split into two singlet states (d_z² and d _x²-y²}), and Fe-3d t_2g were split into one doublet states(d_xz and d_yz) and one singlet states(d_xy) after Fe and O displaced along the c axis. Meanwhile the occupation numbers of d_z², d_yz, d_xz and O_T p_z (on the top of Fe) were increased at the expense of those in xy plane. Our results showed that it was the sensitivity of hybridization to ferroelectric distortions, not just the total change of hybridization, that produced the possibility of ferroelectricity. Moreover, the increasing occupation numbers of O_T p_z and Fe d_z² favoured the 180^o coupling between Fe-3d e_g and Fe-3d t_2g, leading to ferromagnetic ordering, which has been confirmed by the increase of magnetic moment by 0.13μ_B per formula unit in the polarized direction. Hence, the magnetization can be altered by the reversal of external electric field.     

Local structure distortion and spin Hamiltonian parameters for Cr3＋-Vzn tetragonal defect centre in Cr3＋ doped KZnF3 crystal

The quantitative relationship between the spin Hamiltonian parameters (D, g_‖, Δg) and the crystal structure parameters for the Cr³⁺—V_Zn tetragonal defect centre in a Cr³⁺:KZnF₃ crystal is established by using the superposition model. On the above basis, the local structure distortion and the spin Hamiltonian parameter for the Cr³⁺—V_Zn tetragonal defect centre in the KZnF_3 crystal are systematically investigated using the complete diagonalization method. It is found that the V_Zn vacancy and the differences in mass, radius and charge between the Cr³⁺ and the Zn²⁺ ions induce the local lattice distortion of the Cr³⁺ centre ions in the KZnF₃ crystal. The local lattice distortion is shown to give rise to the tetragonal crystal field, which in turn results in the tetragonal zero-field splitting parameter D and the anisotropic g factor Δg. We find that the ligand F^- ion along [001] and the other five F^- ions move towards the central Cr³⁺ by distances of Δ₁ = 0.0121 nm and Δ₂ = 0.0026 nm, respectively. Our approach takes into account the spin—orbit interaction as well as the spin—spin, spin—other-orbit, and orbit—orbit interactions omitted in the previous studies. It is found that for the Cr³⁺ ions in the Cr³⁺:KZnF₃ crystal, although the spin—orbit mechanism is the most important one, the contribution to the spin Hamiltonian parameters from the other three mechanisms, including spin—spin, spin—other-orbit, and orbit—orbit magnetic interactions, is appreciable and should not be omitted, especially for the zero-field splitting (ZFS) parameter D.     

O2分子吸附的金属表面的O2(1Δg)猝灭

建立了一套流动装置测量单重态氧O₂(¹Δ_g)在O₂分子吸附的金属Cu、Cr、Ni和Ag表面的猝灭几率. 随实验时间和O₂(¹Δ_g)浓度增加,猝灭几率增加. 当上述金属样品在几帕斯卡的真空度下暴露数小时后猝灭几率会回到原先水平. 提出了一种基于表面吸附位上弱化学吸附的表面吸附氧分子O₂(¹∑_{g相似文献}   

Spectroscopic investigations on NO+(x1∑+,a3∑+,A1Ⅱ) ion using multi-reference configuration interaction method and correlation-consistent sextuple b

Three low-lying electronic states (x¹∑⁺,a³∑⁺,and A¹Ⅱ) of NO⁺ ion are studied using the complete active space self-consistent-field (CASSCF) method followed by highly accurate valence internally contracted multi-reference configuration interaction (MRCI) approach in combination of the correlation-consistent sextuple basis set augmented with diffuse functions, aug-cc-pV6Z. The potential energy curves (PECs) of the NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) are calculated. Based on the PECs, the spectroscopic parameters R_e, D_e, ω_e, ω_eχ_e, α _e, B_e, and D₀ are reproduced, which are in excellent agreement with the available measurements. By numerically solving the radial Schrödinger equation of nuclear motion using the Numerov method, the first 20 vibrational levels, inertial rotation and centrifugal distortion constants of NO⁺(x¹∑⁺,a³∑⁺,A¹Ⅱ) ion are derived when the rotational quantum number J is equal to zero (J = 0) for the first time, which accord well with the available measurements. Finally, the analytical potential energy functions of these states are fitted, which are used to accurately derive the first 20 classical turning points when J = 0. These results are compared in detail with those of previous investigations reported in the literature.     

用CARS技术确定拉曼退偏比的一种数据处理新方法

Yuika等人利用偏振CARS技术可以准确地确定分子的拉曼退偏比.其方法是，首先对不同检偏角_d所对应CARS谱峰的频率分布进行数学模拟，然后由所得系数随检偏角φ_d的变化求得使CARS信号中共振项消失的偏振角φ^０_d，最后由消失条件ρ＝-1/(tanθtanφ⁰_d)求出退偏比ρ，θ为产生CARS光的Pump光与Stokes光偏振方向的夹角.本文提出的数据处理方法，即交点法.同Yuika等人处理数据的方法相比，交点法毋需关于谱峰频率分布的知识，做法也更为简便.     

Be9(d,p),(d,t),(d,a)反应研究

本文在E_d=0.1—2.5MeV能量范围内,研究了Be⁹(d,p₀)Be¹⁰(0),Be⁹(d,p₁)Be¹⁰(3.368MeV),Be⁹(d,t₀)Be⁸(0),Be⁹(d,α₀)Li⁷(0)及Be⁹(d,α₁)Li⁷(0.478MeV)诸反应。在E_d=0.150,0.220,0.401,0.706,1.005,1.301,1.484,1.750,2.000,2.250和2.500MeV共十一个能量上分别测量了这五群出射粒子在θ_L=10—155°区间的角分布。在θ_L=135°,E_d=0.1—2.5MeV,在θ_L=95°,E_d=0.1—2.2MeV,和在θ_L=112.5°,E_d=0.5—2.5MeV测量了Be⁹(d,p₀)Be¹⁰的激发函数。在θ_L=135°和112.5°,E_d=1.2MeV,用较厚靶(100—300μg/cm²)测量了Be⁹(d,p₀)Be¹⁰(0)反应的截面绝对值,结果为σ_(p0)(θ_L=135°)=1.60mb/sr,σ_(p0)(θ_L=112.5°)=1.55mb/sr。这样就得到了在此能区内,这五群出射粒子的截面情况。对所得结果进行了一些讨论。     

VO分子2△3/2—12△3/2电子跃迁P线系发射谱线的研究

本文利用孙卫国课题组建立的能精确计算(预言)某双原子分子电子态P线系发射谱线的物理新公式,首次研究了VO分子从电子态~2△3/2跃迁到电子态1~2△3/2的(0,0)跃迁带中的P线系发射谱线.获得的研究结果不仅重复了实验上己知的低转动态谱线数据,而且还正确预言了该跃迁带在实验上难以精确测量的转动量子数J=80.5以内的高振转激发态的P线系发射光谱.为研究VO分子内部结构提供了重要的物理信息.     

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.     

锶原子互组跃迁谱的实验研究

观测了热原子束中锶原子(5s²)¹S₀—(5s5p)³P₁ 互组跃迁的荧光谱和饱和荧光谱, 实验测定了不同的参量下 ⁸⁸Sr(5s²)¹S₀—(5s5p)³P₁ 互组跃迁荧光谱. 研究结果表明: 不同的实验参数(温度、激光光强、激光扫描频率)对谱线有较大的影响, (5s5p)³P₁态的长寿命特点导致谱线强度随激光扫描频率呈倒数关系变化; 由于Doppler增宽, 渡越增宽等因素的影响, 谱线线宽远大于其自然线宽且随激光扫描频率呈正比关系变化.     

用差分收敛法研究NaLi分子部分电子态的完全振动能谱

基于双核分子振动能级的普遍表达式和差分收敛法(difference converging method, DCM), 利用微分思想将DCM应用于双核分子体系完全振动能谱的研究中. 应用DCM方法, 分别选用实验上获得的一组(10条)精确的振动能级, 对NaLi分子3¹Π, 4¹Π 和A¹Σ⁺电子态进行了研究, DCM的研究结果正确重复了已知数据并预测出了在实验上未能获得的包含高激发态在内的完全振动能谱数据, 同时计算得到了这3个电子态的振动光谱常数.     

用能量自洽法研究双原子分子离子XY+的五阶解析势能函数

将用于研究双原子分子离子XY⁺解析势能函数的能量自洽法(energy consistent method for ion XY⁺,ECMI)从三阶推广到五阶,并将双原子分子离子XY⁺的三阶解析势能函数ECMI(3)推广为五阶的解析势能函数ECMI(5),研究CO⁺的B²Σ⁺态和SO⁺的b⁴Σ^-态的解析势能函数.结果表明,CO⁺的B²Σ⁺态和SO⁺的b⁴Σ^-态的新解析势能函数ECMI(5)势与基于实验的RKR数据符合得很好,优于常用的中性双原子分子势能函数Morse势、HMS势和双原子分子离子XY⁺的ECMI(3)势在这两个离子状态下的表现.不仅如此,ECMI势给出了对原子分子碰撞等诸多研究非常重要的正确理解极限和全程势能数据.     

用可变阶数的代数方法研究双原子体系的完全振动能谱和离解能

不同双原子分子电子态的势能(或振动能谱)的展开性质可能不同,文章将固定阶数的代数方法(AM)改进为可变阶数的代数方法,使得该方法可以研究各种不同性质(不同能量展开阶数)的双原子分子电子态,也可以解决光谱计算中可能出现的"蝴蝶效应"问题。利用阶数可变的AM方法研究了原来固定阶数的AM方法难以给出正确结果的N2-a′1Σu-,Li2+-2 2Σg+,4 He D+-X1Σ+和39 K85 Rb-(2)3Σ+等不同双核体系的完全振动能谱与离解能,不但得到了与实验数据精确相符的理论结果,还正确地预言了许多由于实验条件与技术原因而未能测得的物理数据。研究表明阶数可变的AM方法能够更广泛地用于研究各类双核电子态体系的完全振动能谱和体系离解能。     

Cl2+离子R支跃迁光谱的理论研究

从双原子分子能级的物理表达式出发进行多次微分,建立了预测双原子分子体系R支高振转跃迁谱线的新解析公式. 使用新解析公式预测双原子体系R支高阶跃迁谱线的数据时,最多只需15条精确的实验跃迁谱线和该跃迁带中对应的上下 振动态的转动光谱常数B′_v 和 B″_v.将该解析公式用于预测Cl₂⁺ 离子 A²∏_u---X²∏_g跃迁系(3,7)带和(4,8)带的跃迁谱线,不仅精确的重复了实验给出的较低阶的跃迁光谱数据值, 而且正确预言了所研究体系中缺失的振转跃迁谱线,尤其是高阶的跃迁谱线数据.     

Accurate studies of dissociation energies and vibrational energies on alkali metals

This paper studies full vibrational spectra {Ev} and molecular dissociation energies De by using conventional least-squares （LS） fitting and an algebraic method （AM） proposed recently for 10 diatomic electronic states of ^7Li2, Na2, NaK and NaLi molecules based on some known experimental vibrational energies in a subset [Ev^expt] respectively. Studies show that： （1） although both the full AM spectrum {Ev^AM} and the LS spectrum {Ev^LS} can reproduce the known experimental energies in [Ev^expt], the {EAM} is superior to the {Ev^LS} in that the high-lying AM vibrational energies which may not be available experimentally have better or much better accuracy than those LS counterparts in {Ev^LS}, and so is the AM dissociation energy De^AM; （2） the main source of the errors in the data obtained by using the LS fitting is that the fitting which is just a pure mathematical process does not use any physical criteria that must be satisfied by the full vibrational spectrum, while the AM method does. This study suggests that when fitting or solving a physical equation using a set of source data, it is important not only to apply a proper mathematical tool, but also to use correct physical criteria which measure the physical properties of the data, kick out those data having bigger errors, and impose conditional convergence on the numerical process.     

OH,OCl,HOCl(~1A′)的从头算与势能曲线

采用Gassian09程序包中的多种方法对OH,OCl,HOCl分子的基态结构进行优化计算,优选出QCISD/6-311G（2df）,B3P86/6-31 1+G（2df）方法分别对OH（X²∏）,OCl（X²∏）分子进行计算,得到平衡核间距R_OH=0.09696nm,R_OCl=0.1569 nm,谐振频率w（OH）=3745.37 cm^-1,e（OCl）=892.046 cm^-1,与实验结果非常符合.用Murrell-Sorbie势能函数对OH和OCl分子的扫描势能点进行拟合,其扫描点都与四参数Murrell-Sorbie函数拟合曲线符合得很好.优选出QCISD（T）/D95（df,pd）方法对HOCl分子进行计算,得到基态为X¹A’,键长R_OH=0.0966 nm,键角∠HOCl=102.3°,谐振频率w₁（a₁）=738.69 cm^-1,w₂（b2）=1260.25 cm^-1,离解能D_e=2.24 eV.通过比较发现这些结果与实验值符合得很好,并优于文献报道的结果.随后计算出了力常数,在此基础上,推导出HOCl分子的多体展式势能函数.报道了HOCl分子对称伸缩振动势能图中在H+OCl→HOCl反应通道上有一鞍点,H原子需要越过1.74 eV的能垒才能生成HOCl的稳定结构,在Cl+OH→HOCl通道上不存在明显势垒,容易形成稳定的HOCl分子.     

OPTICAL-OPTICAL DOUBLE-RESONANCE EXCITATION SPECTRA OF THE (6d)1Πg, (7d)1Πg HIGH-LYING RYDBERG STATES IN Na2

Two ¹Π_g states of Na₂ for v≤13 have been observed by using optical-optical double resonance (OODR) fluorescence excitation spectroscopy. The intermediate levels in B¹Π_u state are identified by the numerical calculations with the molec-ular constants for B¹Π_u←X¹Σ_g⁺ transitions and confirmed by the complemen-tary A¹Σ_g⁺←X¹Σ_g⁺ polarization spectra. Absolute vibrational numberings of the (6d)¹Π_g and (7d)¹Π_g states are determined by comparing the experimental OODR excitation intensities with the simulated Franck-Condon factors. The Dnnham coef-ficients and the Rydberg-Klein-Rees (RKR) potential energy curves of the (6d)¹Π_g, (7d)¹Π_g states are reported.