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1.
任延琦  王启新  张庆刚  张怿慈 《物理学报》1993,42(10):1580-1586
在相互作用表象中,利用角动量耦合理论,导出了原子-振子散射的含时量子计算公式,并计算了He-H2体系的振转激发态-态跃迁几率和分散射截面。结果表明:(1)相互作用表象波函数在坐标空间中具有较高的定域性,随时间演化几乎不变形,因此在计算散射量时具有很高的精度,与标准的密耦合(CC)法的计算结果符合很好;(2)增加的振动部分对计算时间的影响取决于对一势能矩阵的积分,而在该积分中仅含基态的计算就能给出较为理想的散射截面,与CC法相比节省近一倍的计算时间。 关键词:  相似文献   

2.
本文利用密耦合波包法对气相原子刚性双原子分子无反应散射做了具体计算。采用总角动量表象,使三维计算降为一维计算。计算得到简化,计算时间缩短,结果与耦密合法符合的良好。  相似文献   

3.
基于一个最新的CH2(X-3A″)势能面,运用切比雪夫波包方法对初始态为(v=0,j=0)的C(3P)+H2(X1∑g^+)→H(2S)+CH(2Π)反应体系在1.0-2.0 eV的碰撞能量范围内进行了动力学研究.通过对角动量量子数J=60以下的所有分波进行计算,得到了反应几率、积分散射截面和速率常数.计算中用到了耦合态近似方法和考虑科里奥利耦合效应的精确量子方法.通过对比发现,随着角动量量子数以及能量的增加,科里奥利耦合效应的影响越发显著,因而对于该反应体系,科里奥利耦合效应不可忽略.本文计算所得的积分散射截面和速率常数尚无实验数据可以比较,对该反应的后续研究有一定的参考价值.  相似文献   

4.
沈光先  汪荣凯  令狐荣锋  杨向东 《物理学报》2011,60(1):13101-013101
采用超分子单双迭代(包括非迭代三重激发)耦合簇理论CCSD(T)方法,选择由原子中心高斯函数和高斯键函数3s3p2d1f组成的大基组,计算了He-H2(D2,T2)碰撞体系的H2分子取不同键长时的相互作用势能面.运用Tang-Toennies势模型和非线性最小二乘法拟合构造了He与同位素分子H2(D2,T2)在质心坐标系下的振转相互作用势.通过密耦计算得 关键词: 高斯键函数 Tang-Toennies势函数 分波截面 碰撞参数  相似文献   

5.
严格交换势用于研究低能电子与H2分子的弹性和非弹性散射截面,线性代数方法和R-矩阵传播子相结合求解基于振动密耦合方法的积分-微分耦合方程组,由此得到收敛的(0→0,0→1,0→2)散射微分截面和积分截面.理论计算结果与目前优秀的实验值和其他理论计算值进行了比较,表明基于振动密耦合方程的严格交换势在低能电子与H2分子振动激发散射中有重要作用. 关键词: 严格交换势 2分子振动激发')" href="#">H2分子振动激发 微分截面 积分截面  相似文献   

6.
用含时波包(TDWP)理论计算了具有两个不同产物道的反应HD+H→H+DH,D+H2的初态确定的反应几率及生咸物的分支比。在利用分解算符法进行波包传播的过程中,采取了分立变量表象(DVR)及分立交量-有限基表象(DVR—FBR)变换,这一方法降低了传播过程中需保存大变换矩阵的要求。通过应用能量投影法,可从单一波包中抽出许多能量确定的动力学信息。为了避免因所选取的格点范围有限而引起的波函数在边界点附近的反射,传播过程中还采用了光学势以吸收反射波函。  相似文献   

7.
贺凯芬  胡岗 《物理学报》1991,40(12):1948-1954
在以驱动波相速度运动的坐标系中,用微扰法讨论。在正弦波驱动下的非线性漂移波的分波方程。结果表明,在文献[1]中观察到的波包能量的滞后分岔和由定态向周期态的分岔可以统一地解析描述,它们分别对应某一非线性共振模式在时间维上的鞍结点分岔和Hopf分岔。波包能量失稳的频率是该模式的本征频率,除多普勒移动外,它的大小还因非线性效应而不同于其在实验室坐标系中的线性值。 关键词:  相似文献   

8.
近些年来引起广泛关注的二维半导体莫尔超晶格系统中存在着莫尔激子、强关联电子态和面外铁电性等新奇物理现象,电子的层间耦合对于理解这些现象至关重要.本文研究了二维半导体双层莫尔超晶格中的层间耦合随位置和动量的变化.外势场导致的局域布洛赫波包的层间耦合与波包宽度以及中心位置处的层间平移有着密切关系.同时,层间耦合随动量的变化使得基态S型波包和激发态P±型波包有着截然不同的随中心位置变化的层间耦合形式:在两个S型波包的层间耦合消失的位置,S和P+型(或S和P-型)波包之间的层间耦合达到最强.利用该性质,可以通过外加光电场来调控特定谷的基态波包的层间输运.此外,双层系统中发现的面外铁电性可以归结为不同层导带和价带间的耦合导致的电子在两层中的再分配现象.将本文得到的层间耦合形式与单层紧束缚模型相结合,可计算出垂直平面的电偶极密度,其随层间平移的变化形式和数量级与实验观测相符.  相似文献   

9.
赵仪  张宏 《化学物理学报》1999,12(2):141-147
用一维两态波包动力学模型从理论上研究了碘分子在两个激光脉冲串作用下有泵浦-拉下过程。计算中碘分子的基态和激发态势能面采用莫尔斯势能面,含时薛定谔方程通过分裂算符快速富里叶变换方法求解,基电子态的振动本征函数采采不连续变量方法计算,初步波包选择为电子基态的振动基本征函数,两个势能面之间的耦合采用偶极近似,激光脉冲的形状选择为高斯脉冲。利用上述的含时波包法实时地模拟了碘分子通过中间B态向基电子X态的高  相似文献   

10.
于坤  张晓美  刘玉芳 《物理学报》2013,62(6):63301-063301
基于相关一致极化4zeta(aug-cc-pVQZ)基组, 应用量子化学从头计算中高水平的多参考组态相互作用方法计算了BCl+ 两个离解极限B+(1Sg)+Cl(2Pu)和B (2Pu)+Cl+ (3Pg)的14个Λ-S态势能曲线. 在计算中考虑了Davidson修正(+Q)和标量相对论效应, 并首次在计算中考虑了BCl+ 的旋轨耦合效应, 获得了由能量最低的4个Λ-S态分裂出的7个Ω 态. 计算结果表明相同对称性的Ω 态的势能曲线存在着非常明显的避免交叉. 通过分析Λ-S态的电子结构, 得到了各态的电子跃迁特性, 并确认了电子态的多组态性质. 使用LEVEL程序通过求解径向的Schrödinger方程得到了束缚Λ-S 和Ω态的光谱参数De, Re, Te, ωe, ωeχe和Be. 通过和已有的Λ-S态X2+ 的实验数据进行对比发现, 本文所得的计算结果与实验结果非常一致. 而文中其他电子态的光谱参数均为首次报道. 关键词: 势能曲线 光谱参数 多参考组态相互作用方法 旋轨耦合  相似文献   

11.
陈海军  任元  王华 《物理学报》2022,(5):268-279
Bessel型光晶格是一种非空间周期性的柱对称的光晶格势场,其兼具无限深势阱和环状势阱的特征,在0阶Bessel光晶格势场中央形成深势阱,而在非0阶Beseel光晶格势场中能形成具有中央势垒的环状浅势阱.极化激元是一种半光半物质的准粒子,该准粒子甚至可以在室温条件下发生玻色-爱因斯坦凝聚相变,形成极化激元凝聚.另外,通过极化激元能级的腔诱导TE-TM分裂能在极化激元凝聚中实现足够强的自旋-轨道耦合作用.极化激元凝聚能在室温条件下实现,在其中又存在自旋-轨道耦合作用,其为量子物理的研究提供了全新的平台.本文把Bessel光晶格势场引入到极化激元凝聚系统,研究了存在自旋-轨道耦合作用下的旋量双组分极化激元凝聚系统的稳态结构.通过求解Gross-Pitaevskii方程给出了极化激元凝聚系统在实验室坐标系和旋转坐标系中极化激元凝聚系统的稳态结构,由于Bessel势场的引入,使得稳态结构更具有多样性.给出了实验室坐标系中在中央深势阱中存在的基础型高斯孤立子、多极孤立子和在环状浅势阱中存在环状孤立子和多极孤立子的稳态结构;给出了旋转坐标系中存在的涡旋环状孤立子,及其由于自旋-轨道相互作用引起的组...  相似文献   

12.
We perform dynamical calculations on two robust N2–N2 potential energy surfaces in order to intercompare pressure broadening coefficients derived from close coupling and coupled states quantum dynamical methods, the semi-classical model of Robert and Bonamy and a full classical method. The coupled states and full classical results compare well with the experimental results or with close coupling values when available. This study confirms that the classical method is a good alternative at room and high temperatures to quantum dynamical methods. The results obtained using the semi-classical method however deviate from the other sets of data at all temperatures considered here (77–2400 K).  相似文献   

13.
We compare the effect of two body core on the charge form factor of3He by the hyperspherical harmonics expansion method using various 2BF potentials with the inclusion of three body force. We also include the meson exchange current contribution to the CFF for the same potentials in addition to the 3BF. The results indicate that the combined effect of 3BF and MEC (i) movesq min 2 (the first diffraction minimum) appreciably to the left, amount of shift depends on the 2BF atr 12∼0.7 fm and (ii) enhancesF max (the height of the secondary maximum of CFF) by an appreciable amount, the increment in general increases with the repulsive core of 2BF (r⩽0.1 fm).  相似文献   

14.
The collisional excitation of the lower vibrational levels of H2(1Σg+) molecules by low-energy electron impact is computed using an empirical model potential and by solving the coupled-channels scattering equations within a space-fixed (SF) frame of reference formulation. Numerically converged partial, integral inelastic and elastic cross-sections are obtained from what is an essentially exact treatment of the dynamics and the results are compared with measurements and with earlier calculations on the same system. The usefulness of the SF method for handling excitation processes at near-threshold collision energies is discussed and analyzed through the calculations of collisional superelastic partial cross-sections down to 10-2 meV of collision energy.  相似文献   

15.
Singlet fission (SF), whereby a singlet exciton is converted into a pair of triplet excitons, can improve the efficiency of solar cells. Pentacene has been extensively studied as the most promising SF compound, owing to its 200% yield of triplet states. However, the easy degradation of pentacene in the presence of light and air owing to photooxidation cannot be explained by the classical 1O2 generation mechanism. To address this issue, in the present study, pentacene nanorods (Pc NRs) are prepared as a novel photosensitizer (PS); self-carried Pc NRs exhibited higher 1O2 generation capacity. Thus, a novel 1O2 generation mechanism is proposed based on the SF effect. The initial photon absorption occurs to access single-exciton states, S1–S3. Excited-state Pc pairs accelerate the SF effect in pentacene NRs, leading to a non-adiabatic transition to the dark D state. Dark D state is a singlet state by two triplets coupled overall, and it can transfer its energy to 3O2 for generating 1O2. Using Pc NRs as PSs, photodynamic therapy (PDT) inhibits tumor growth in 4T1 tumor-bearing mice upon 405-nm-wavelength and 650-nm-wavelength laser irradiations. This study paves the way to discover novel PSs that are not considered with classical 1O2 generation mechanisms.  相似文献   

16.
陈东猛  刘大勇 《物理学报》2010,59(10):7350-7356
基于自旋-轨道-晶格Hamilton量,应用团簇自洽场方法,研究了双层钙钛矿结构材料K3Cu2F7基态的晶格、磁及轨道结构,发现近孤立的双层的对称破缺和Jahn-Teller晶格畸变使得Cu2+离子在每层内交替占据 z2-x2〉/ z2-y2〉轨道,进而导致双层的层间表现为强的反铁磁耦合,层内为弱的铁磁耦合.强反铁磁耦合导致层间  相似文献   

17.
We have simulated the Gibbs-Vrehen-Hikspoors observations of quantum beat superfluorescence (SF) from the 7P→7S transitions in Cs vapour by extending the previous numerical work on semi-classical 2-level atom SF to particular 3-and 4- level atom models. Beats at the spacing of the two upper levels modulate the SF from a 3-level model consisting of two close upper levels sharing a common lower level. Lower state beats modulate the SF from a 4-level model consisting of two separated upper levels coupled independently to two lower levels. Results for the leading SF pulse are in good qualitative agreement with the experiments.  相似文献   

18.
We have observed superfluorescence (SF) on five atomic transitions at visible wavelengths 633.58, 635.00, 640.09, 640.61 and 736.22 nm in Doppler broadened gas of europium (Eu) atom. The nanosecond SF pulses were observed by longitudinally pumping Eu vapor column with a pulsed dye laser to upper states 4f65d6s2, 8D7/2at 346.79 nm and 4f75d6p, 10F5/2at 348.73 nm from the ground state 4f76s2, 8S7/2. High optical conversion efficiency ≈10% was measured for these SF transitions. Our experiment deals with the large sample multilevel SF in the regime where the length of the excited column L is greater than the maximum value of the Arecchi-Courtens length (Lc). The observed variation of SF peak intensity (Ifl) and time delay for SF evolution (τD) with number of atoms in the excited state (N) resemble theoretically predicted SF scaling laws for transverse excitation, namely Ifl∝N and tD μ 1/?N\tau_D \propto 1/{\sqrt N} although the experimental condition is similar to the swept excitation. This could be due to the Rabi frequency associated with the pump transition which is comparable to the SF delay time precluding the initiation of SF at different times along the sample and results in transverse (instantaneous) excitation. The experimental τD values were found to be in agreement with the quantum mechanical calculations describing SF.  相似文献   

19.
Quantum close coupling (CC) calculations of H2-broadening coefficients of infrared and isotropic Raman lines of acetylene (C2H2) are performed for temperatures between 77 and 2000 K. They are used to test three more approximate methods, the quantum coupled states (CS) theory, the semiclassical Robert-Bonamy (RB) formalism and the full classical (FC) model of Gordon. In order to allow a clear and well founded comparison, all the dynamical calculations were performed employing the same ab initio potential energy surface free of any adjustable parameters. It is shown that below room temperature both the coupled states method and full classical method fail at reproducing the close coupling pressure broadening coefficients while above room temperature they are correct and predict comparable accurate values for temperatures greater than about 1000 K. The values provided by the RB method are clearly not satisfactory even at the highest temperature examined. However, the temperature dependence of the RB results follows the functional form used for interpolating and extrapolating CC, CS and FC pressure broadening coefficients.  相似文献   

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