THEORETICAL STUDY OF REACTION DYNAMICS OF H_2 ■ H+H ON LITHIUM(100) SURFACE

A generalized LEPS potential energy surface of (H_2?H +H)/Li(100) plane systemwas constructed based on the ab initio SCF absorption and surface diffusion of a hydrogenatom on lithium(100) surface, and reaction kinetic behaviour of this system was investigatedby means of QCT method. It was shown from analysis of the feature of this potential energysurface that the activation energy of absorption of H_2 molecules on a lithium(100) planeis unnecessary and the dissociation of H_2 on the Li(100) plane relates closely to the adsorp-tion sites and adsorption fashions, and the horizontal manner of dissociation of H_2 is easierthan the standing one. And it was also shown from the analysis of various collision trajec-tories that the surface recombination probabilities of bi-hydrogen atoms at low covering arevery small, and that the surface dissociation probabilities of H_2 are controlled by its vibra-tional quantum number. The potential energy surface of gas-metal surface interaction systemconstructed here is con     

多原子强离子键KX(X = OH, NC)及(KX)2体系电子相关能的简单计算

通过MELD程序MP2-OPT2方法在6-311++G(d)及6-311++G(3df, 3pd)基组下对KX(X = OH, NC)体系对内对间电子相关能的计算结果和分析, 并根据KX(X = OH, NC)分子中K和X组分的内层电子对相关能和内层电子相关效应的传递性, 定义并且计算了K^δ +和K^δ -对KX分子体系的电子相关能贡献. 基于K⁺, X-和KX(X = OH, NC)的对相关能的比较结果, 提出了利用其组成金属离子和负离子基团的电子相关能之和来计算多原子强离子键分子体系电子相关能的简单计算方法, 此方法对Gaussian98程序MP2(full)/6-311++G(d)水平下二聚体系(KOH))₂和(KNC))₂的电子相关能的近似计算结果误差很小, 应用此“化整为零”的方案计算大分子离子键体系电子相关能既可以基本达到化学计算要求的精度又能节约大量的计算工作量.     

Study on Pair Correlation Energies of Isoelectronic Systems F^－, HF and H2F^＋

The intrapair and interpair correlation energies of F-, HF and H2F^ systems are calculated and analyzed using MP2-OPT2 method of MELD program with cc-PVSZ^* basis set. From the analysis of pair correlation energies of these isoelectronlc sysoterns, it is found that the 1sF^2 pair correlation energy is trans-ferable in these three isociectronic systems. According to the definition of pair correlation contribution of one electron pair to a system, the pair correlation contribution values of these three systems are calculated. The correlation contribution values of inner electron pairs and H—F bonding electron pair in HF molecule with those in H2F^ system are compared. The results indicate that the bonding effect of a molecule is one of the im-portant factors to influence electron correlation energy of the system. The comparison of correlation energy contributions in-cluding triple and quadruple excitations with those only includ-ing singles and doubles calculated with 6-311 G(d) basis set shows that the higher.excitation correlation energy contribution gives more than 2 % of the total correlation energy for these sys-tems.     

H+O2(n0, j0)→HO+O及C+H2(n0, j0)→CH+H体系选态反应截面的过渡态理论计算

本文用微正则过渡态理论计算了H+O_2(n_0,j_0)→HO+O和C+H_2(n_0, j_0)→CH+H在ab initio势能面上的选态反应截面σ_(n_0,j_0); E.分析了势能面性质对反应截面的影响。计算结果表明, 在指定反应物分子的振动态n_0、转动态j_0时, 两个反应体系的反应截面随相对平动能的增加先是增加后是减小(j_0=1, n_0=0除外); 在给定相对平动能和反应物分子的转动态j_0时, 随反应物分子的振动量子数n_0的增加, 两个体系的选态反应截面均有较显著的增加, 在指定相对平动能和反应物分子的振动态n_0时, H+O_2体系的选态反应截面随j_0的变化较为复杂, 而C+H_2体系则比较简单(j_0=1除外)。对于H+O_2反应体系, 本文得到的反应截面与实验结果及准经典轨迹理论的计算结果符合得很好。     

用变分过渡态理论研究NH_3+NH→2NH_2反应动力学

利用变分过渡态理论的“直接动力学”方法对ＮＨ３分子和基态ＮＨ（Ｘ３∑）自由基的反应进行了理论研究；利用从头算计算得到反应体系的电子结构能和能量梯度等信息，计算了２００～２５００Ｋ温度范围该反应的速率常数和穿透系数，分析了影响隧道效应和反应速率常数的一些因素．结果表明，在低温情况下，变分对于此反应影响较大，隧道效应特别明显．计算得到的速率常数和实验值符合得很好．     

State(R)-state(TS)-state(P) theoretical study of H+H_2 system

The calculation of H + H2 system by symplectic quasiclassical trajectory (SQCT) shows that there are two types of collision trajectories A and B, i.e., type A trajectory passes the saddle point of transition state (TS), whereas type B trajectory does not pass the saddle point of transition state. Not all the reactants of type A trajectory are reactive, while not all of type B trajectory are nonreactive. The partition and reactivity of these two types of trajectories are affected by reactant state(R), furthermore, the types of trajectories affect the state and angle distributions of products. Not only the rudiment framework for theoretical study on state(R)-state(TS)-state(P) is established, but also the further understanding of transition state theory (TST) of Eyring is investigated in this paper.     

次甲基硅SiH与HF反应的热力学及动力学性质研究

在量子化学对SiH与HF反应计算的基础上,运用统计热力学和Wigner校正的Eyring过渡态理论计算了该反应在200～2000K温度范围内的热力学函数、平衡常数、频率因子A和速率常数随温度的变化。计算结果表明该反应在低温下具有热力学优势,而在高温下具有动力学优势。该反应在研究的温度范围内是一放热、熵减少的反应,反应的速率常数随温度的升高而增大,且服从Arrhenius定律。     

辛准经典轨迹法研究Cl+H2反应

用辛准经典轨迹法模拟了Cl+H2反应在mBW2势能面上的动力学行为。研究了各种初始条件下的反应碰撞截面,产物的能量分配,角度分布和态分布。另外,我们还比较了反应物的三种能量形式(平动能,转动能和振动能)对反庆的有效性。     

Intra- and interpair electron correlation --Analysis of the G1 and G2 theories

The irrationality of the HLC correction in the G1 and G2 theories has been analyzed concretely and deeply. Meanwhile, how to improve the Post-HF calculation has been pointed out.     

氢原子共线交换反应的动力学计算I.Cl与HCl反应几率的振荡现象研究

我们利用超球坐标对共线Cl+HCl(V-3)→ClH(V'≤3)+Cl作了一维精确量子计算,计算所用势能面是LEPS型,Et=-3.23KJ/mol, 得到了态态反应几率等动力学信息, 通过分析结果发现, 反应是振动绝热的, 即以对角(V'-V')反应几率为主,非对角(V' V')反应几率小于0.1, 反应几率随总能量表现出强裂地振荡, 在有阱的势能面上动力学共振增强。