| 查看: 1327 | 回复: 6 | |||
| 本帖产生 1 个 翻译EPI ，点击这里进行查看 | |||
| 当前只显示满足指定条件的回帖，点击这里查看本话题的所有回帖 | |||
[交流]
adiabatic or diabatic Potential energy surfaces 相关翻译！
|
|||
|
英语太蹩脚，加上专业词汇多，困难太大，请各位高手帮忙！ Potential energy surfaces can be of two types: adiabatic or diabatic. Adiabatic surfaces are defined within the Born–Oppenheimer approximation by the energy (eigenvalue) of a given solution to the electronic Schrodinger equation at each geometry. Such solutions are obtained by using the full electronic Hamiltonian, that is, including kinetic energy, Coulomb, scalar relativistic and spin–orbit terms. Diabatic surfaces can be defined as generated from the eigenvalues of the Schrodinger equation solved using a Hamiltonian from which one or more terms have been omitted; in the present case, the spin–orbit coupling terms. Surfaces of both types are shown for a notional spin-forbidden reaction in Fig. 1. Reactants are on diabatic surface 1 (e.g. corresponding to a triplet state), with products on surface 2 (e.g. a singlet). The corresponding minima have different geometries, and the surfaces cross at the Minimum Energy Crossing Point (MECP). The adiabatic surfaces A and B in Fig. 1 do not cross, as the spin–orbit coupling matrix element H12 = <Ψ1|Hsoc|Ψ2> is non-zero and, therefore, when Hsoc is included in the Hamiltonian, the eigenfunctions are mixtures of different spin states. This means that, in principle, there is a well-defined transition state on the lower surface. In extreme cases, spin–orbit coupling may indeed be so strong that the mixing takes place over a broad range of geometries around the TS, and the reaction can in fact be described in the usual way using standard TST. In practice, for very many cases, the mixing is rather weak and non-adiabatic, non-Born–Oppenheimer behaviour will occur: the system will undergo ‘hops’ from one surface to the other. These can be described either in terms of the diabatic surfaces, as sudden changes in spin state, or in terms of the adiabatic surfaces, as sudden hops from the lower adiabatic surface, A, to the upper one, B. For example, in the limit of very weak spin-orbit coupling, a system approaching the crossing region from the reactant side is most likely, in diabatic terms, to remain on surface 1, and then return to reactants. In adiabatic terms, when the system approaches the very narrowly-avoided crossing between surfaces A and B it will ‘hop’ onto the upper surface. Upon returning from right to left on the diagram, it will hop again at the avoided crossing, back onto surface A and thereby head back to reactants. These two descriptions are equivalent, with the second perhaps more natural to theoretical chemists, but with the first more convenient for our purposes. We will therefore use the diabatic framework throughout. In this terminology, for reaction to occur, spin–orbit coupling must induce a ‘hop’ from surface 1 to surface 2 as the system goes through the crossing region. Hops can occur at any position along the reaction coordinate, but are more likely in the small region around the crossing point where the two surfaces are close in energy. |
回复此楼» 猜你喜欢
磺酰氟产物，毕不了业了！
已经有4人回复
-
论文终于录用啦！满足毕业条件了
已经有16人回复
-
求个博导看看
已经有19人回复
-
投稿Elsevier的杂志（返修），总是在选择OA和subscription界面被踢皮球
已经有8人回复
wanggang126(金币+30):莫非你是研究这类的？留个QQ以后多多向你请教！ 2010-05-07 23:30:16
|
The adiabatic surfaces A and B in Fig. 1 do not cross, as the spin–orbit coupling matrix element H12 = <Ψ1|Hsoc|Ψ2> is non-zero and, therefore, when Hsoc is included in the Hamiltonian, the eigenfunctions are mixtures of different spin states. This means that, in principle, there is a well-defined transition state on the lower surface. In extreme cases, spin–orbit coupling may indeed be so strong that the mixing takes place over a broad range of geometries around the TS, and the reaction can in fact be described in the usual way using standard TST. In practice, for very many cases, the mixing is rather weak and non-adiabatic, non-Born–Oppenheimer behaviour will occur: the system will undergo ‘hops’ from one surface to the other. These can be described either in terms of the diabatic surfaces, as sudden changes in spin state, or in terms of the adiabatic surfaces, as sudden hops from the lower adiabatic surface, A, to the upper one, B. 图一中的绝热势能面A和B不相交，因为旋-轨耦合矩阵元H12= <Ψ1|Hsoc|Ψ2>不为零，因此当旋-轨项Hsoc包括在哈密顿中时，本征函数由不同自旋态混杂而成。这就意味着，理论上，低势能面上有一个定义良好的过渡态。在极端的情况下，旋-轨耦合可能真的强到混杂可以在过渡态附近宽泛的几何构型间发生，反应其实可以用标准的过渡态理论（TST）描述。实际上，在很多情况下，混杂很弱，将会发生非绝热、非波恩-奥本海默行为：系统将从一个势能面“跃迁”至另一个势能面。这种情况可以用非绝热势能面描述，如自旋态突变，或用绝热势能面描述，如突然从低能量的绝热势能面A跃迁至高能绝热势能面B |
4楼2010-05-06 00:14:38
2楼2010-05-05 15:13:00
wanggang126(金币+30, 翻译EPI+1):翻译的挺好，挺专业，大概能明白其中的意思了，太感谢你了！ 2010-05-07 23:28:39
|
Potential energy surfaces can be of two types: adiabatic or diabatic. Adiabatic surfaces are defined within the Born–Oppenheimer approximation by the energy (eigenvalue) of a given solution to the electronic Schrodinger equation at each geometry. Such solutions are obtained by using the full electronic Hamiltonian, that is, including kinetic energy, Coulomb, scalar relativistic and spin–orbit terms. Diabatic surfaces can be defined as generated from the eigenvalues of the Schrodinger equation solved using a Hamiltonian from which one or more terms have been omitted; in the present case, the spin–orbit coupling terms. Surfaces of both types are shown for a notional spin-forbidden reaction in Fig. 1. Reactants are on diabatic surface 1 (e.g. corresponding to a triplet state), with products on surface 2 (e.g. a singlet). The corresponding minima have different geometries, and the surfaces cross at the Minimum Energy Crossing Point (MECP). 势能面分为绝热和非绝热两种。绝热势能面是在波恩-奥本海默近似的框架内定义的，指的是在每个几何构型下，电子薛定谔方程的本征值，即能量。上述方程解对应全电子哈密顿算符，即包括电子动能，库仑，标量相对论和旋-轨各项。非绝热势能面可以由使用省略某（些）项的哈密顿的薛定谔方程的本征值解获得；这里省略的是旋-轨项。图一展示自旋禁阻反应模型的两种势能面。反应物在非绝热势能面1上（如，代表一个三重态），产物在势能面2上（如，某个单重态）。相对应的能量最小值处于不同的几何构型，势能面相交于最小能量交叉点（MECP）处。 [ Last edited by c111999 on 2010-5-6 at 00:15 ] |
3楼2010-05-05 23:55:07
wanggang126(金币+10):本来打算全部给你金币的，但鉴于楼下的朋友也费力不少，希望能理解！还是要感谢你的帮助！ 2010-05-07 23:34:00
|
For example, in the limit of very weak spin-orbit coupling, a system approaching the crossing region from the reactant side is most likely, in diabatic terms, to remain on surface 1, and then return to reactants. In adiabatic terms, when the system approaches the very narrowly-avoided crossing between surfaces A and B it will ‘hop’ onto the upper surface. Upon returning from right to left on the diagram, it will hop again at the avoided crossing, back onto surface A and thereby head back to reactants. These two descriptions are equivalent, with the second perhaps more natural to theoretical chemists, but with the first more convenient for our purposes. We will therefore use the diabatic framework throughout. In this terminology, for reaction to occur, spin–orbit coupling must induce a ‘hop’ from surface 1 to surface 2 as the system goes through the crossing region. Hops can occur at any position along the reaction coordinate, but are more likely in the small region around the crossing point where the two surfaces are close in energy. 例如，在极弱旋-轨耦合极限，当系统从反应物一侧接近交叉区域，用非绝热术语表述为系统很有可能继续待在势能面1上，然后返回成反应物。用绝热术语表述为，当系统进入势能面A与B间非常窄的擬交差区域，系统将跃迁至上层势能面。一旦在图中从右向左回到擬交差区域，系统会再次跃迁至势能面A并且在此返回反应物。这两种描述是等价的，第二种对于理论化学工作者更自然，但是第一种更便于达到我们的目的。我们将通篇使用非绝热框架。依此术语，为了让反应进行，在系统通过交叉区域，旋-轨耦合必然引发从势能面1至2的跃迁。跃迁可以在反应坐标上的任意某处发生，然而在两个势能面接近交叉点附近的小范围内更有可能。 [ Last edited by c111999 on 2010-5-6 at 00:37 ] |
5楼2010-05-06 00:31:07