Highest occupied orbital

Most electronic valence transitions shift to longer wavelengths at higher pressures drat is, the gap between the highest occupied orbital and lowest unoccupied orbital tends to decrease upon compression. The rates of shift usually are larger (1) for pure materials than for solutes in a solvent and (2) for stronger (more allowed) transitions. However, these correlations are not quantitative, and many transitions shift in the opposite... 

Not all Iterative semi-empirical or ah iniiio calculations converge for all cases. For SCF calculation s of electronic stnictiire. system s with a small energy gap between the highest occupied orbital and the lowest unoccupied orbital may not converge or may converge slowly. (They are generally poorly described by the Ilartree-Foch method.)... 

The. more tightly held an electron is. the more difficult it is to remove, hence the higher the electrode potential necessary to remove it. Make the reasonable hypothesis that the electron removed in a one-electron oxidation comes from the highest occupied orbital. HOMO. Using SHMO. determine the HOMO for ben7 ene, biphenyl, and naphthalene. 

Orbitals 7 and 9 (the latter is the LUMO) of formaldehyde exhibit this same character. Orbital 7 is a bonding 7t orbital, and orbital 9 is a Tt . However, the n orbital formed of the pj orbitals from the carbon and the oxygen (which also lie in the YZ plane) is not the HOMO. Instead, an orbital formed from Pj, orbitals from the carbon and the oxygen and from the s orbitals on the hydrogens is the highest occupied orbital. The contributions from the carbon and oxygen are situated along the double bond while the HOMO in ethylene was perpendicular to this bond. 

In standard Hiickel n -electron theory, the highest occupied orbital has a node through the position of C3 and so we might expect a zero proton hyperfine coupling constant, even after using McConnell s argument. 

The three highest occupied orbitals of sulfoxides are the lone pairs ns and n0, as well as the 7iso bond210. The 1,3-dithietane 1-oxide adds a lone-pair ionization and destabilizes the n0 and nso radical-cation states compared with thietane oxide. According to a hyperconjugative MO model, the ns+ combination in 1,3-dithietane is destabilized by about leV relative to the basis orbital energy a(ns) due to the combination with the... 

Lowest-unoccupied orbital of diene (top) overlaps highest occupied orbital of "alkene" (bottom)... 

We shall call a radical each system having one unpaired electron and of course an odd number of electrons. In terms of simple MO methods, that means a system having in its ground state one electron in the highest occupied orbital. According to the nature of that orbital, we classify a and jt radicals. 

Figure 9-3. Schematic representation of the occupations of the highest occupied orbitals dominating the wave functions of singlet and triplet carbene. For the singlet, q > c2.

NHO next-highest occupied (orbital) IP ionization potential x) CNDO calculation... 

On the other hand, asymptotic density of the corresponding Kohn-Sham system is determined completely by the highest occupied orbital and is given as... 

Negative of the Highest Occupied Orbital Eigen Energies (Atomic Units) of Some Atoms Calculated with the Potential Wx Equation 7.34... 

Extension of this method for correcting the energies of approximate wave functions to systems containing more electrons and orbitals would be very useful. But difficulties quickly arise. The interelectronic effects become complicated because of exchange and correlation. More importantly, in DFT, it is only the highest occupied orbital whose energy is equal to the electronic chemical potential. This potential is valid for the total electron density. 

For polyenes in their ground state, the highest occupied MO (HOMO) will be symmetric with respect to m2 for 2, 6, 10. .. n electron systems and antisymmetric for 4, 8, 12. .. n electron systems. The lowest unoccupied MO (LUMO) has the symmetry opposite to that of HOMO. In the first excited state, the LUMO of the ground state will become singly occupied because of the promotion of an electron and it will thus become the new highest occupied orbital. Therefore in the circumstances the symmetry of the highest occupied orbital is opposite to that of the ground state. 

The mercury lamp has been the conventional light source used in photochemistry. The ground-state mercury atom, Hg, has two electrons in its highest occupied orbital, the 6s atomic orbital. Excited mercury... 

---