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adiabatic or diabatic Potential energy surfaces 相關(guān)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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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(gòu)型下，電子薛定諤方程的本征值，即能量。上述方程解對應(yīng)全電子哈密頓算符，即包括電子動能，庫侖，標(biāo)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(yīng)模型的兩種勢能面。反應(yīng)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(yīng)的能量最小值處于不同的幾何構(gòu)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(dāng)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(gòu)型間發(fā)生，反應(yīng)其實可以用標(biāo)準(zhǔn)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
wanggang126(金幣+10):本來打算全部給你金幣的，但鑒于樓下的朋友也費力不少，希望能理解！還是要感謝你的幫助！ 2010-05-07 23:34:00
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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，在極弱旋-軌耦合極限，當(dāng)系統(tǒng)從反應(yīng)物一側(cè)接近交叉區(qū)域，用非絕熱術(shù)語表述為系統(tǒng)很有可能繼續(xù)待在勢能面1上，然后返回成反應(yīng)物。用絕熱術(shù)語表述為，當(dāng)系統(tǒng)進入勢能面A與B間非常窄的擬交差區(qū)域，系統(tǒng)將躍遷至上層勢能面。一旦在圖中從右向左回到擬交差區(qū)域，系統(tǒng)會再次躍遷至勢能面A并且在此返回反應(yīng)物。這兩種描述是等價的，第二種對于理論化學(xué)工作者更自然，但是第一種更便于達到我們的目的。我們將通篇使用非絕熱框架。依此術(shù)語，為了讓反應(yīng)進行，在系統(tǒng)通過交叉區(qū)域，旋-軌耦合必然引發(fā)從勢能面1至2的躍遷。躍遷可以在反應(yīng)坐標(biāo)上的任意某處發(fā)生，然而在兩個勢能面接近交叉點附近的小范圍內(nèi)更有可能。 [ Last edited by c111999 on 2010-5-6 at 00:37 ] |
5樓2010-05-06 00:31:07
xxsst888
銅蟲 (小有名氣)
- 翻譯EPI: 7
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- 金幣: 2042.2
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wanggang126(金幣+30):雖然你翻譯的不是很如我意，但你也費力不少，故贈30BB,聊表心意，謝謝你的幫助！ 2010-05-07 23:36:11
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溶液中 勢能表面的絕熱和非絕熱現(xiàn)象 溶液的勢能表面可分為兩種;絕熱表面和非絕熱表面�？梢杂脦缀纹矫姹硎尽＝^熱表面特定值能用給定溶液的能量來決定，其值近似于由Schrodinger電子方程算出的 Born-Oppenheimer特征值 。此溶液可按表示電子的Hamiltonian函數(shù)獲得，其中函數(shù)條件要包括動能，庫倫電量，標(biāo)量相對論和自旋軌道理論。而求非絕熱表面特定值時可省略一到二個函數(shù)條件 �，F(xiàn)在的例子忽略自旋軌道耦合項，兩種類型的表面顯示的是理論上的自旋禁止反應(yīng)，圖 1 。反應(yīng)物在非絕熱表面1（對應(yīng)于三重態(tài)），其產(chǎn)品在表面2（單態(tài)），相應(yīng)的最小值有不同的幾何圖形，而且，其表面穿過最小能量節(jié)點（EMCP） 做為自旋軌道耦合模型，元素H12=《w1 / Hsoc /w2》 不等于零，而且，Hsoc也包含在Hamiltonian函數(shù)中。如果這個特征函數(shù)是不同自旋狀態(tài)下的混合的話，那么圖1中絕熱面A和B不相交。這表明在通常情況下，低的表面有明顯的過渡態(tài)。在極端情況下，自旋軌道耦合是如此的強以至混合能在試驗裝置內(nèi)大范圍進行，反應(yīng)也可以用標(biāo)準(zhǔn)測試來記錄。實際上，對大多數(shù)實驗而言，混合的情況是弱的，散熱的，和不符合Born-Oppenheimer現(xiàn)象的。該混合體系經(jīng)歷從一個表面到另一個表面的“躍遷”經(jīng)歷。我們可以用下面兩種方式說明絕熱和非絕熱現(xiàn)象：其一，非絕熱表面說明的是自旋狀態(tài)，或者，絕熱表面說明的是躍遷狀態(tài)。 例如，在非常弱的自旋軌道耦合范圍內(nèi)，混合體系從反應(yīng)物一方接近節(jié)點區(qū)時，若以非絕熱方法解釋，傾向于保持在表面1上，然后再恢復(fù)到反應(yīng)物一方。另一方面，用絕熱方法解釋，混合體系非常接近表面A和表面B之間的將要接近的區(qū)域時，弱自旋軌道耦合將產(chǎn)生躍遷而到上層表面B，圖中從右到左所示，為了避免接觸形成節(jié)點區(qū),自旋軌道耦合將再躍遷一次返回到表面A，也就是向反應(yīng)物一方躍遷。這兩種解釋是相等的，第二種解釋為理論化學(xué)家所傾向，但第一種解釋為實驗人員所考慮。所以，我們將以非絕熱為基礎(chǔ)，用這個術(shù)語時能說明當(dāng)反應(yīng)發(fā)生時，形成混合體系將要通過節(jié)點區(qū)，但自旋軌道的耦合必定誘發(fā)從表面1到表面2的躍遷。躍遷可在反應(yīng)坐標(biāo)內(nèi)任何位置發(fā)生，但更傾向于在節(jié)點附近兩個表面能量相似的小區(qū)域內(nèi)發(fā)生。 （你有設(shè)備做此實驗---但愿你有） |
6樓2010-05-06 15:51:10
7樓2010-05-07 23:39:09
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