Diabatic and adiabatic potential

And what will happen for q t)l It depends on where the extra electron resides. If it is still on the second molecule (which means it is H2), then 0 means an elongation of an already-too-long H2 and a shortening of an already-too-short Hj. The potential energy goes up and the total plot is similar to a parabola with the minimum at = 0 0. If, however, we assume that the extra electron resides all the time on the first of the molecules, then we will obtain the identical parabolalike curve as before, but with the minimum position at = — 0 0. freeze all the translations and rotations. 

Whether the adiabatic or diabatic potential has to be applied is equivalent to asking whether the electron will keep pace adiabatic) or not (diabatic) with the motion of die nuclei This is within the spirit of the adiabatic approximation, cf. Chapter 6, p. 253. Also, a diabatic curve corresponding to the same electronic 

Intermolecular Motion of Electrons and Nuclei Chemical Reactions 

Structure (the extra electron sitting on one of the molecules all the time) is an analogue of the diabatic hypersurface that preserved the same chemical bond pattern encountered before. 

Similar conclusions come from another ideal system, namely the hydrogen fluoride molecule treated as the pendulum of a grandfather clock (the hydrogen atom down, the clock axis going through the fluorine atom) moving over two molecules A and B, one of them accommodates an extra electron (Fig. f4.2i.b). 

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Song L, Gao J (2008) On the construction of diabatic and adiabatic potential energy surfaces based on ab initio valence bond theory. J Phys Chem A ASAP... 

Cattaneo, P, Persico, M., Diabatic and Adiabatic Potential Energy Surfaces for Azomethane Photochemistry, Theor. Chem. Acc. 2000, 103, 390 398. 

The explicit choice of which terms to neglect is not unique. For example, diabatic and adiabatic potentials are bases for two quite different but equally useful zero-order pictures. These two models and the reasons for selecting one over the other are discussed in Section 3.3. What appears as a large deviation from one zero-order model may be vanishingly small for another. Consequently, the definition of a perturbation depends critically on one s choice of zero-order model, which is often a matter of personal preference. 

Electromagnetic Field-Dressed Diabatic and Adiabatic Potential Energy Curves. 177... 

Figure 3.5 Diabatic and adiabatic potential curves. The diabatic curves (solid lines) cross at Rc and are defined by neglecting the part of Hel that causes the adiabatic curves (dotted lines) to avoid crossing by 2if at Rc-...

Once rotational constants are obtained from the sharpest lines, trial diabatic and adiabatic potentials are refined until the rotational constants, Bd and Bad, calculated from them satisfy Eq. (7.12.5). Figure 7.37 shows that the exact solutions of the coupled equations give a width that is not proportional to (He)2 when the coupling becomes very strong. One can understand this by varying the electronic matrix element. As He increases, the adiabatic level shifts. When it has shifted into coincidence with the diabatic level, the width is zero according toEq. (7.12.6). 

MO and AD pictures (p. 805) reaction stages (p. 806) role of states DA, D+A , D+A (p. 811) HOMO-LUMO crossing (p. 815) nucleophilic attack (p. 816) electrophilic attack (p. 818) cycloaddition reaction (p. 823) Woodward-Hoffmann rules (p. 825) Diels-Alder reaction (p. 825) diabatic and adiabatic potentials (p. 828) inverse Marcus region (p. 833) collective coordinate (p. 836) mean force potential (p. 836) Franck-Condon factors (p. 840) reorganization energy (p. 841)... 

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