Lowest unoccupied molecular orbital energy level

Lovasz-Pelikan index spectral indices (0 eigenvalues of the adjacency matrix) LOVIs = LOcal Vertex Invariants local invariants Lowdin population analysis quantum-chemical descriptors Lowest-Observed-Effect Level biological activity indices (0 toxicological indices) lowest unoccupied molecular orbital quantum-chemical descriptors lowest unoccupied molecular orbital energy quantum-chemical descriptors LUDI energy function scoring functions Lu index —> hyper-Wiener-type indices... 

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].

When designing the electrolyte solvent and salt compounds one can consult the molecular orbital methods with some programs such as the Gaussian [63]. The molecular orbital method calculates the most stable conformation as well as the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) levels of the compound concerned. Figure 2.11 indicates the relationship between molecular orbitals and their energy levels in a molecule. When the oxidation takes place an electron is ranoved from the HOMO. When the reduction occurs an electron is inserted into the LUMO. Therefore, the lower HOMO level... 

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... 

The most extensive calculations of the electronic structure of fullerenes so far have been done for Ceo- Representative results for the energy levels of the free Ceo molecule are shown in Fig. 5(a) [60]. Because of the molecular nature of solid C o, the electronic structure for the solid phase is expected to be closely related to that of the free molecule [61]. An LDA calculation for the crystalline phase is shown in Fig. 5(b) for the energy bands derived from the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) for Cgo, and the band gap between the LUMO and HOMO-derived energy bands is shown on the figure. The LDA calculations are one-electron treatments which tend to underestimate the actual bandgap. Nevertheless, such calculations are widely used in the fullerene literature to provide physical insights about many of the physical properties. 

Fig. 9 OMT bands for NiOEP, associated with transient reduction (1.78 V) and transient oxidation (—1.18 V). Data obtained from a single molecule in a UHV STM. The ultraviolet photoelectron spectrum is also shown, with the energy origin shifted (by the work function of the sample, as discussed in [25]) in order to allow direct comparison. The highest occupied molecular orbital, n, and the lowest unoccupied molecular orbital, %, are shown at their correct energy, relative to the Fermi level of the substrate. As in previous diagrams,

Figure 1 shows the electron attachment energies (AE) and ionization potentials (IP) of silyl substituted 7t-systems and related compounds [4], AE can be correlated with the energy level of the LUMO (lowest unoccupied molecular orbital) and IP can be correlated with the energy level of the HOMO (highest occupied molecular orbital). For a-substituted 7t-systems, the introduction of a silyl group produces a decrease in the tc -(LUMO) level. This effect is attributed to the interaction between a low-lying silicon-based unoccupied orbital such as the empty d orbital of silicon and the it orbital (d -p interaction) as shown in Fig. 2. Recent investigations on these systems, however, indicate that d orbitals on silicon are not necessarily required for interpreting this effect a-effects of SiR3 can also be explained by the interaction between Si-R a orbitals and the 7r-system.

In the course of investigation of reactivity of the mesoionic compound 44 (Scheme 2) the question arose if this bicyclic system participates in Diels-Alder reactions as an electron-rich or an electron-poor component <1999T13703>. The energy level of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) orbitals were calculated by PM3 method. Comparison of these values with those of two different dienophiles (dimethyl acetylenedicarboxylate (DMAD) and 1,1-diethylamino-l-propyne) suggested that a faster cycloaddition can be expected with the electron-rich ynamine, that is, the Diels-Alder reaction of inverse electron demand is preferred. The experimental results seemed to support this assumption. 

Fig. 2.1. Energy levels of molecular orbitals in formaldehyde (HOMO Highest Occupied Molecular Orbitals LUMO Lowest Unoccupied Molecular Orbitals) and possible electronic transitions.

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