Highest occupied molecular orbital HOMO level

The nature of the electronic states for fullerene molecules depends sensitively on the number of 7r-electrons in the fullerene. The number of 7r-electrons on the Cgo molecule is 60 (i.e., one w electron per carbon atom), which is exactly the correct number to fully occupy the highest occupied molecular orbital (HOMO) level with hu icosahedral symmetry. In relating the levels of an icosahedral molecule to those of a free electron on a thin spherical shell (full rotational symmetry), 50 electrons fully occupy the angular momentum states of the shell through l = 4, and the remaining 10 electrons are available... 

Realizing the need for further improvements, design guidelines have been proposed for the synthesis of new low-bandgap conjugated copolymers with deeper highest occupied molecular orbital (HOMO) level (to harvest more incident photons), so that both Jsc (short-circuit current density) and Voc (open-circuit voltage) can be maximized [232,272]. This... 

Figure 1. Energy diagrams for FeS, ZnS, and MnS as potential donors of photo-excited electrons (left column) and for the biologically relevant electron acceptors (right column). The Highest Occupied Molecular Orbital (HOMO) level in the ence bands of each semiconductor is shown by a darker color than the respective Lowest Unoccupied Molecular Orbital (LUMO) level in the conduction band. The picture is based on data from references [72,99,122,262,264].

The aim of model theories [51], which predict band offsets through the macroscopic parameters of the materials, is to find or specify a reference energy level ( r) for the metals and semiconductors. Upon formation of the heterojunction, one merely hues up the reference levels in the two materials. In this case, the valence band offset between two materials is simply obtained as the difference between the two valence band maxima, measured relatively to such a reference level. enables one to define an absolute scale for all semiconductors or metals. Once is calculated, we need to know only the semiconductor s valence band maximum Ev (or the highest occupied molecular orbital (HOMO) levels in molecules) relative to for each material, which following Tersoff s approach [51] we denote as ... 

In Eq. (1), / is the maximum current that can run through the cell. The open circuit voltage (V ) depends on the highest occupied molecular orbital (homo)level of the donor (p-type semiconductor quasi Fermi level) and the lowest unoccupied molecular orbital(lumo) level of the acceptor (w-type semiconductor quasi Fermi level), linearly. P in is the incident light power density. FF, the fill-factor, is calculated by dividing P by the multiplication of / and V and this can be explained by the following Eq. (2) ... 

At the donor/acceptor interface (step III in Figure 5), exciton D is quenched via electron transfer to the lowest unoccupied molecular orbital (LUMO) level of the acceptor molecule (A°). On the contrary, exciton A is quenched via hole transfer to the highest occupied molecular orbital (HOMO) level of the donor molecule (D ). Both pathways result in the formation of the same charge separated state D+ A . Positive and negative charges in this ion pair are bond by Coulomb attraction forces and also denoted as geminate polaron pair. This pair can dissociate in the electric field induced by the potential jump at the heterojunction and/or by the difference in the electrode work functions. At the same time, the energy difference... 

For the He atom, when the KS equation is solved with the exact potential as shown in Figure 2, the highest occupied molecular orbital (HOMO) level is at —24.592eV, the negative of the ionization energy of helium. In exact DFT, Koopmans theorem, which states I = —eHOMO, is exactly true. In ground-state DFT, this is the only energy level of the fictitious KS system that has an immediate physical interpretation. 

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