Calculated first singlet excitation energy

Figure 2. Calculated (INDO/S) first singlet excitation energy all-trans [(CHj)2Si]n (dot-dash) all-Irons [H2Si]n (full) all-gauche [H2Si]n (dashed).

A model for the light/dark behavior of GFP has been proposed [40]. It is based on quantum mechanical calculations of the energy barriers for the cp and z one-bond flips (OBF) and the (p/z hula twists (HTs) that were calculated in the ground and first singlet excited states for a small nonpeptide model compound. Figure 5.5 shows the calculated energy profiles. 

As an illustration of the performance of TDDFT, we compare various density functionals and wave function methods for the first singlet excited states of naphthalene in Tables 4, 5, and 6. All calculations were performed using the aug-TZVP basis set, while the complete active space self-consistent field (SCF) with second-order perturbation theory (CASPT2) results from Ref. 200 were obtained in a smaller double-zeta valence basis set with some diffuse augmentation. The experimental results correspond to band maxima from gas-phase experiments however, the position of the band maximum does not necessarily coincide with the vertical excitation energy, especially if... 

The results of these calculations show that the excited states of benzene fall into three classes covalent, ionic, and Rydberg. An example of a covalent state is the first singlet excited state, B2 , lying at an energy of 4.90 eV above the ground state. It may be represented to an excellent approximation simply as ... 

In Table 2 we summarize the results of the DDCI calculations on the lowest excitation energies for terrace, step and comer F and F+ centers. As expected, for a given transition the excitation energy decreases as the coordination of the defect decreases. For F centers, the allowed singlet to singlet lowest transition occurs at 3.4 eV for the surface, 2.9 eV for the step and 2.6 eV for the comer. The same trend is found for the F+ centers, where the first doublet to doublet transition, goes from 3.6 eV for the surface, to 2.6 eV for the step and 2.4 eV for the comer. As observed previously for the bulk calculations, excitations for the F+ centers appear around 0.2 eV below the excitations due to F centers. The excitations at the step and comer sites are shifted about 0.5-1.2 eV compared to... 

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