表面活性剂与聚合物相互作用的动力学模拟

用扩散颗粒动力学模拟方法（Dissipative Particle Dynamics，DPD）模拟了 中性聚合物与离子型表面活性剂的相互作用。在分子水平上研究了介于微观和宏观 上的一些性质，直观地用三维图形描绘了聚合物在表面活性剂溶液中的聚集形成， 并通过聚合物的末端的变化表征了聚集过程。结果发现：随着表面活性剂浓度的增 加，聚合物呈现自由伸缩→形成松散的棒状结构→再出现胶束状珍珠链结构→最终 在六角状和层状相中分布的过程。DPD模拟方法能够直观地得到聚合物在表面活性 剂溶液中的聚集形态。     

An Ab initio Theoretical Study on the Nonadiabatic Coupling for Na＋I2 Collision System

The ionic and neutral state potential energy surfaces (PESs) of Na I2 collision system have been calculated on QCISD(T) level by using ab initio method.The location and depth of the potential well,the collision radius and their fine structures have been analyzed at the equilibrium geometry of I2 molecule.The electronic transfer probabilities are also calculated in terms of Landau-Zener model.The lifetime of scattering resonance state is evaluated by the uncertainty principle.All the results have been compared with those obtained according to the Aten-Lanting-Los PES and Feng‘s PES.     

组氨酸残基在芳基胺类N-乙酰基转移酶（NATs）乙酰化过程中有何作用？——量子化学研究

Arylamine N-acetyltransferases(NATs,EC 2.3.1.5)catalyze an acetyl group transfer from acetyl coenzyme A(AcCoA)to primary arylamines and play a very important role in the metabolism and bioactivation of drugs andcarcinogens.Experiments revealed that His-107 was likely the residues responsible for mediating acetyl transfer.The full catalytic mechanism of acetylation process has been examined by density functional theory.The results in-dicate that,if the acetyl group is directly transferred from the donor,p-nitrophenyl acetate,to the acceptor,cysteine,the high activation energy will be a great hindrance.These energies have dropped in a little range of 20—25 kJ/molwhen His-107 assisted the transfer process.However,when protonated His-107 mediated the reaction,the activa-tion energies have been dropped about 73—85 kJ/mol.Our calculations strongly supported an enzyme acetylationmechanism that experiences a thiolate-imidazolium pair,and verified the presumption from experiments.     

一种计算Feshbach共振态寿命的新方法

在自然碰撞坐标下构建偏分势能面, 利用数值传播方法求解沿反应坐标的核运动方程, 然后用过渡态波函数的相移因子构造反应体系共振态寿命矩阵. 这是一种直接计算化学反应散射共振寿命的量子散射方法. 用此方法计算了I+HI(υ)→IH(υ’)+I体系的第一散射共振态寿命, 所得数值与Neumark 的高分辨阈值光分离光谱实验的结果相一致.     

[Mn(H_2O)_4(NCS)_2]·(18-C-6)配合物晶体的电子结构与成键特性理论研究

本文取配合物晶体[Mn(H_2O)_4(NCS)_2]·(18-C-6)的一个分子片断进行CNDO/2半经验分子轨道理论计算,给出Mulliken键级、电荷分布和电子态密度等,探讨了其成键特性。结果表明,过渡金属配合单元[Mn(H_2O)_4(NCS)_2]与18-C-6冠醚环之间的主要结合方式是定域化程度相当高的氢键,与来自实验测量的推测相一致。     

NH3R^＋＋NH42（4=H,CH3）体系质子传递反应的从头算研究

用从头计算法在ＨＦ／６－３１Ｇ基组水平上研究了ＮＨ４＾＋＋ＮＨ３→ＮＨ３＋ＮＨ４＾＋，ＮＨ４＾＋＋ＮＨ２ＣＨ３→ＮＨ３＋ＮＨ３ＣＨ３＾＋，ＮＨ４＾＋＋ＮＨ（ＣＨ３）２→ＮＨ３＋３）２＾＋以及ＮＨ３ＣＨ３＾＋＋ＮＨ２ＣＨ３→ＮＨ２ＣＨ３＋ＮＨ３ＣＨ３＾＋等４个体系的质子传递反应的机理。结果表明：（１）上述质子传递反应均具有双阱型的势能面，质子沿Ｎ（１）、Ｎ（２）连线直接传递；（２）质子受体分子中的甲     

[Co(H2O)4(NCS)2]·(18-C-6)配合物晶体的成键特性理论研究

[Co(H_2O)_4(NCS)_2]·(18-C-6)是本文作者之一最近合成的新王冠醚配合物晶体。我们用CNDO/2方法计算了该配合物原子簇模型的电荷分布, Mulliken键级,电子态密度(DOS)等,研究其成键特性。结果表明, 该配合物中存在稳定的[Co(H_2O)_4(NCS)_2]·(18-C-6)集团, 配合单元[Co(H_2O)_4(NCS)_2]采取四根强度不同的氢键与(18-C-6)相结合, 并较好地解释了实验结果。     

STUDY ON THE DYNAMICS OF H+O_2 SYSTEM AT LOW COLLISION ENERGY

In this paper, the process of the reactive collision of the atom H (~2S) with the moleculeO_2(~3∑_g~-) has been simulated on the ab initio potential surface, and the dynamics of thissystem has been studied at low collision energy, E = 0.3eV, with O_2 in quantum statesv(vibration quantum number) = 2, j(rotational quantum number) = 1, 20, 40, 60, 80, 100.The results of calculations have shown: (1) the maximum impact parameter at which thereaction occurs is 4. 5a_0, (2) the impact parameter b at which the reaction probability ismaximum decreases as j increases, (3) the reaction cross section monotonically increasesas j increases, (4) for inelastic collisions, in which b is small and j is large, both thevibration v' and rotation quantum numbers j' of the product O_2 fall down obviously, andfor reactive collisions, the products OH(~2π) are almost in vibration ground states, but theprobabilities of excited vibration states increase obviously as j increases, and the populationinversion even appears at j = 10     

H+O_2体系在低碰撞能下的动力学研究

本文用准经典轨迹理论,模拟了H(~2S)原子与O_2(~3Σ_g~-)分子在ab initio势能面上的反应碰撞过程,研究了该反应体系在低碰撞能E=0.3eV,O_2的量子态v(振动量子数)=2,j(转动量子数)=1,20,40,60,80,100时的动力学行为。计算结果表明:(1)发生反应的最大碰撞参数b_(max)为4.5a_o,(2)产生最大反应几率的碰撞参数b随j的增加而减小,(3)反应截面随j单调增加,(4)对于小b高j时的非弹性碰撞,产物O_2的振动量子数v′和转动量子数j′均明显地下降,而对于反应碰撞,产物OH(~2Π)多处于基振动态(v′=0),且随j的增加,产物OH处于振动激发态(v′>0)的几率明显增加,当j=100时,甚至出现振动态分布倒反现象。此外,还绘制了部分典型的碰撞轨迹图。