Orbital definition

It should be noted, however, that the use of a spin-symmetry-adapted determinant such as the ROHF wavefunction as a reference in a coupled cluster calculation does produce a spin-pure energy, but does not imply that the correlated wavefunction itself is an eigenfunction of as well. For the spin-orbital definition of T described here, spin contamination can still enter into the coupled cluster wavefunction through the nonlinear contributions of cluster operators to the amplitude equations, though the importance of this... 

The term species may mean a discrete molecule, a simple or complex ion or even a solid exhibiting non-molecularity in one or more dimensions (graphite as an example). Free atoms seldom act as Lewis acids and bases. They usually have one or more unpaired electrons and flieir reactions are more accurately classified as free radical. The donor orbital is usually die highest occupied molecular orbital HOMO, and the acceptor orbital is usually the lowest unoccupied molecular orbital or LUMO. The molecular orbital definitions have a number of important consequences ... 

We could use the spin orbital definition (3.115) of f ti, coi) to perform these integrations and work out explicit formulas for / and Alternatively,... 

Figure 5. a. Orbital definitions for the four-electron-four-orbital system, b. MO manifold for the four-electron-four-orbital system, c. Schematic MO and MOVB representations of the low lying valence states of the four-electon-four-orbital system. 

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