Level shift, model potential

When working with the final model potentials of equations (10) and (11) in molecular applications, we are interested in valence properties and, in fact, do not need to include core orbitals in our wavefunction any more. This is so, since core-valence interaction has been accounted for implicitly in equation (10), and the sum of energies of individual cores with fixed orbitals is a constant, anyway. However, in order to get an aufbau principle for the valence wavefunction, core orbitals > have to be shifted from energies c to energies above those of the (occupied) valence ones, and this level-shift is done by... 

The procedure above can work only if the effect of the level shift is negligible in the stable case when no intruder state appears. Otherwise, we have introduced a new parameter into the model over which we have no control. The behavior of the level-shifted CASPT2 approach has recently been tested in a series of calculations on the N2 and Ct2 molecules [26]. The first test was performed on the potential curve for the... 

However, experimental ]V curves often deviate from the ideal /scl- In these cases, the measured current /inj is injection limited caused by a nonohmic contact or poor surface morphology. When the MO interface is nonohmic, carrier injection can be described by the Richardson-Schottky model of thermionic emission the carriers are injected into organic solid only when they acquire sufficient thermal energy to overcome the Schottky barrier ((()), which is related to the organic ionization potential (/p), the electron affinity (AJ, the metal work function (O, ), and the vacuum level shift (A) [34,35]. Thus, the carrier injection efficiency (rj) can be calculated by the following equation ... 

The interface between the quasi-metal PEDOT PSS and organic semiconductors has been investigated in numerous experiments. As illustrated in Figure 14.16, the energy barrier for hole injection (AE) is not simply determined by the difference between the PEDOT PSS work function (4>) and the ionization potential (/ ) of the semiconductor as predicted by the Schottky-Mott model dipole layer formation at the interface will lead to a vacuum level shift A [158-161]. 

We will use the term pseudopotential for this kind of potential. In the second, the core orbitals are removed to a very high energy by a level-shifting procedure. As a result, any tendency of the valence orbitals to gain core character is energetically unfavorable. This second method was developed under the name ab initio model potentials (AIMP), though in some quarters this method is also referred to as an effective eore potential or pseudopotential method. We will refer to these potentials as model potentials. The form of the potential is... 

The same sort of treatment as for ordinary metallic bulk matter can also be applied to surface core-level shifts. The surface atoms experience a different potential compared to the layers below because of the lower coordination number. This results in somewhat different core level binding energies. One can extend the previous Born-Haber cycle model to account for the surface-bulk core level shift. Empirically, the surface cohesive energy is approximately 80% of the bulk value. The impurity term can then be written as... 

In order to explain the changing optical properties of AIROFs several models were proposed. The UPS investigations of the valence band of the emersed film support band theory models by Gottesfeld [94] and by Mozota and Conway [79, 88]. The assumption of nonstoichiometry and electron hopping in the model proposed by Burke et al. [87] is not necessary. Recent electroreflectance measurements on anodic iridium oxide films performed by Gutierrez et al. [95] showed a shift of optical absorption bands to lower photon energies with increasing anodic electrode potentials, which is probably due to a shift of the Fermi level with respect to the t2g band [67]. 

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