Highest occupied crystal orbital

In combination with contact metals such as Ag or Au, tetracene exhibits hole transport only, because of the matching between the metal workfrinction and the tetracene HOCO highest occupied crystal orbital). The hole mobility can be independently estimated from the saturation of the output curve... 

HBC (hexabenzocoronene) 62,213 HBC-C12 62 ff. high vacuum 429 ff highest occupied crystal orbital (HOCO) 549... 

The highest-occupied crystal orbital is known as the Fermi level it is equivalent to the HOMO of the crystal. The two levels HOMO and LUMO are fundamental as always-they... 

We sometimes find a thermodynamic definition of the Fermi leveL but in this book, it will always be the highest-occupied crystal orbital. 

So, both models of polyacetylene lead to the same predictions as to electronic structure. We start at energy a + 2p and then progress through to an energy of precisely a. Note also that both models predict that the band gap. Eg, the energy gap between the highest occupied crystal orbital and the lowest unoccupied crystal orbital, should be precisely zero. This is an important finding that we will return to below. 

Where are the electrons We ha ve six electrons per monomer to distribute, and these are used to fill bands 1-3. Bands 4-6 are empty. Band 3, therefore, is the valence band because it contains the highest occupied crystal orbital, and band 4 is the conduction band. The Fermi level Ep lies at the zone center in this system, while it is at the zone edge for polyacetylene. There is no real-world significance to this distinction. One very meaningful distinction between polyacetylene and PPP, however, is evident at HMO level. By inspection you can see that the highest occupied and lowest unoccupied crystals orbitals should not be degenerate in the case of PPP. PPP has a finite band gap in HMO theory, while polyacetylene does not. 

In an extended structure (solid, metal, semiconductor, or insulator), the average of the highest occupied and lowest unoccupied levels. In chemistry, the Fermi level is usually considered as the highest occupied crystal orbital. 

The lowest excited states in molecular crystals are singlet and triplet excitons [3]. Since it costs coulombic energy to transfer an electron that has been excited optically from the HOMO (highest occupied molecular orbital) to the LUMC)... 

Each energy level in the band is called a state. The important quantity to look at is the density of states (DOS), i.e. the number of states at a given energy. The DOS of transition metals are often depicted as smooth curves (Fig. 6.10), but in reality DOS curves show complicated structure, due to crystal structure and symmetry. The bands are filled with valence electrons of the atoms up to the Fermi level. In a molecule one would call this level the highest occupied molecular orbital or HOMO. 

Bk(R) intrinsic crystal-field parameters HOMO Highest Occupied Molecular Orbital... 

---