Diabatic state regularized

It is not the purpose of this article to give a systematic account of all aspects of the theory and construction schemes for diabatic states. Rather, after this somewhat historic introduction, we will outline salient features of the theory in Sec. 2 and refer to other chapters in this book (especially Chapter 1 by L. S. Cederbaum) and earlier review articles for more details. Section 3 gives an overview over existing construction schemes with an attempt to characterize their respective merits and emphasis. Section 4 is devoted to a more detailed exposition of the concept of regularized diabatic... 

Pig. 5. Contour line drawing of a diagonal (a) and the off-diagonal (b) diabatic potential matrix element for the Ryl" and 2 A states of ozone, taken from Ref. 40. The bond lengths ri and T2 are varied, while the bond angle is fixed at 120°. Dashed lines represent the reference data of Woywood et al. full lines result from the concept of regularized diabatic states. 

The photodissociation on coupled potential surfaces of H2S has also been treated in Ref. 40 and a similarly good agreement (with the reference data of Simah et alJ ) has been obtained. As applications of the concept of regularized diabatic states we mention work on Rydberg emission spectra of and on photodetachment spectra of N02. While the diabati-... 

Fig. 6. Comparison of reference data (dashed lines, from Ref. 81) with results from the concept of regularized diabatic states (full lines, from Ref. 40) for the Chappuis band of ozone. In panel (a), the vibronic coupling constant A has been determined in an extended portion of the C2v subspace in panel (b), it has been computed along the seam only. For more details see text.

Kdppel H, Schubert B (2006) The concept of regularized diabatic states for a general conical intersection. Mol Phys 104 1069... 

The import of diabatic electronic states for dynamical treatments of conical intersecting BO potential energy surfaces is well acknowledged. This intersection is characterized by the non-existence of symmetry element determining its location in nuclear space [25]. This problem is absent in the GED approach. Because the symmetries of the cis and trans conformer are irreducible to each other, a regularization method without a correct reaction coordinate does not make sense. The slope at the (conic) intersection is well defined in the GED scheme. Observe, however, that for closed shell structures, the direct coupling of both states is zero. A configuration interaction is necessary to obtain an appropriate description in other words, correlation states such as diradical ones and the full excited BB state in the AA local minimum cannot be left out the scheme. 

The diagonal elements of the EVB hamiltonian correspond to the diabatic energies of the valence bond states and are given by a regular force field expression... 

The diabatic excited state population P2 shows rather regular oscillation for 4 times before becoming steadily decreasing after 300 fs. We note that the steady decrease in population beyond 300 fs is due to the wavefunction dissociating from the excited state (which is unphysical, see Sec. 5.4.1.1) and not from population transfer to the V surface. 

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