Evaluation of xd and Gad clarifies and quantifies the electronically adiabatic nature of PT when the relevant nuclear coordinate for the combined ET-PT reaction could be the proton displacement and is around the order of 1 To get a pure ET reaction (also see the useful comparison, inside the context of ET, of the electronic and nonadiabatic couplings in ref 127), x in Figure 24 may be a nuclear reaction coordinate characterized by larger displacements (and thus bigger f values) than the proton coordinate in electron-proton transfer, but the relevant modes commonly have significantly smaller frequencies (e.g., 1011 s-1; see section 9) than proton vibrational frequencies. Consequently, according to eq 5.56, the electronic coupling threshold for negligible xd(xt) values (i.e., for the onset from the adiabatic regime) can be significantly smaller sized than the 0.05 eV value estimated above. Nevertheless, the V12 worth decreases around exponentially with the ET distance, along with the above evaluation applied to typical biological ET systems results in the nonadiabatic regime. In general, Iprodione Technical Information charge transfer distances, specifics of charge localization and orientation, coupled PT, and relevant nuclear modes will identify the electronic diabatic or adiabatic nature of your charge transfer. The above discussion gives insight into the physics and the approximations underlying the model system employed by Georgievskii and Stuchebrukhov195 to describe EPT reactions, however it also delivers a unified framework to describe various charge transfer reactions (ET, PT, and EPT or the particular case of HAT). The following points that emerge in the above discussion are relevant to describing and understanding PES landscapes connected with ET, PT, and EPT reactions: (i) Smaller sized V12 values produce a larger variety with the proton- solvent conformations on every single side of the intersection between the diabatic PESs exactly where the nonadiabatic couplings are negligible. This circumstance results in a prolonged adiabatic evolution from the charge transfer program over every single diabatic PES, exactly where V12/12 is negligible (e.g., see eq 5.54). Nonetheless, smaller V12 values also create stronger nonadiabatic effects close sufficient to the transition-state coordinate, where 2V12 becomes considerably bigger than the diabatic energy difference 12 and eqs 5.50 and 5.51 apply. (ii) The minimum power separation in between the two adiabatic surfaces increases with V12, plus the effects of the nonadiabatic couplings lower. This implies that the two BO Boc-Glu(OBzl)-OSu site States turn out to be excellent approximations with the exact Hamiltonian eigenstates. Rather, as shown by eq five.54, the BO electronic states can differ appreciably in the diabatic states even near the PES minima when V12 is sufficiently massive to ensure electronic adiabaticity across the reaction coordinate range. (iii) This basic two-state model also predicts rising adiabatic behavior as V12/ grows, i.e., because the adiabatic splitting increases as well as the energy barrier (/4) decreases. Even when V12 kBT, so that the model leads to adiabatic ET, the diabatic representation may well still be hassle-free to make use of (e.g., to compute power barriers) provided that the electronic coupling is much much less than the reorganization energy. five.three.3. Formulation and Representations of Electron- Proton States. The above analysis sets circumstances for theReviewadiabaticity of the electronic element of BO wave functions. Now, we distinguish involving the proton coordinate R and yet another collective nuclear coordinate Q coupled to PCET and construct mixed elect.