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adiabatic or diabatic Potential energy surfaces 相關翻譯！
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英語太蹩腳，加上專業(yè)詞匯多，困難太大，請各位高手幫忙！ 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. |
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7樓2010-05-07 23:39:09
2樓2010-05-05 15:13:00
wanggang126(金幣+30, 翻譯EPI+1):翻譯的挺好，挺專業(yè)，大概能明白其中的意思了，太感謝你了！ 2010-05-07 23:28:39
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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). 勢能面分為絕熱和非絕熱兩種。絕熱勢能面是在波恩-奧本海默近似的框架內(nèi)定義的，指的是在每個幾何構型下，電子薛定諤方程的本征值，即能量。上述方程解對應全電子哈密頓算符，即包括電子動能，庫侖，標量相對論和旋-軌各項。非絕熱勢能面可以由使用省略某（些）項的哈密頓的薛定諤方程的本征值解獲得；這里省略的是旋-軌項。圖一展示自旋禁阻反應模型的兩種勢能面。反應物在非絕熱勢能面1上（如，代表一個三重態(tài)），產(chǎn)物在勢能面2上（如，某個單重態(tài)）。相對應的能量最小值處于不同的幾何構型，勢能面相交于最小能量交叉點（MECP）處。 [ Last edited by c111999 on 2010-5-6 at 00:15 ] |
3樓2010-05-05 23:55:07
wanggang126(金幣+30):莫非你是研究這類的？留個QQ以后多多向你請教！ 2010-05-07 23:30:16
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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. 圖一中的絕熱勢能面A和B不相交，因為旋-軌耦合矩陣元H12= <Ψ1|Hsoc|Ψ2>不為零，因此當旋-軌項Hsoc包括在哈密頓中時，本征函數(shù)由不同自旋態(tài)混雜而成。這就意味著，理論上，低勢能面上有一個定義良好的過渡態(tài)。在極端的情況下，旋-軌耦合可能真的強到混雜可以在過渡態(tài)附近寬泛的幾何構型間發(fā)生，反應其實可以用標準的過渡態(tài)理論（TST）描述。實際上，在很多情況下，混雜很弱，將會發(fā)生非絕熱、非波恩-奧本海默行為：系統(tǒng)將從一個勢能面“躍遷”至另一個勢能面。這種情況可以用非絕熱勢能面描述，如自旋態(tài)突變，或用絕熱勢能面描述，如突然從低能量的絕熱勢能面A躍遷至高能絕熱勢能面B |
4樓2010-05-06 00:14:38
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