Excited state configurations

The coefficients indicate the composition of the electronic state in terms of a linear combination of the various electronic configurations defined earlier in the output. Here is an example from a 4,4 CAS showing the first two excited state configurations ... 

Excited-state configurations are perfectiy vaiid as iong as they meet the restrictions given in Table. In the electrical discharge of a sodium vapor lamp, for instance, we find some sodium atoms in excited states with configurations such as 2 2 3 p or 2 2 p 3 These configurations use valid orbitals a... 

C08-0060. For nitrogen, how many different excited-state configurations are there in which no electron has > 2 Write all of them. 

Of the many quantum chemical approaches available, density-functional theory (DFT) has over the past decade become a key method, with applications ranging from interstellar space, to the atmosphere, the biosphere and the solid state. The strength of the method is that whereas conventional ah initio theory includes electron correlation by use of a perturbation series expansion, or increasing orders of excited state configurations added to zero-order Hartree-Fock solutions, DFT methods inherently contain a large fraction of the electron correlation already from the start, via the so-called exchange-correlation junctional. 

However, in a large number of closed shell molecules, a single Slater determinant describes the ground state wave function fairly accurately. Even in such cases inclusion of excited state configuration results in substantial lowering of total electronic energy, and this is referred to as nondynamic electron correlation. 

Neglecting the filled low-energy o-orbitals, the electronic configuration of the lowest electronic state (the ground state) is tt2n2. Photon absorption of the appropriate energy results in excited-state configurations by promotion of one electron from an occupied molecular orbital... 

The excited state configuration is likely to be n, -n as judged from the capability of the excited nitro group to abstract hydrogens which are in no way activated. Lack of activation, however, is overcompensated by the close proximity of the potential reaction partners. Although quantum yields of disappearance of starting material would be highly desirable, so far only quantum yields of formation of products [i.e. N-hydroxy-2-indolinones) have been obtained. 

In a more advanced treatment beyond the single-Slater determinant Hartree-Fock limit, additional determinants corresponding to excited-state configurations are added to the wave function. If the occupied spin orbitals are labeled a, b, c, etc., and the unoccupied orbitals r, s, t, etc., a single excited configuration representing excitation from orbital a to orbital r is given by... 

One approach is to construct a more flexible description of electron motions in terms of a combination of Hartree-Fock descriptions for ground and excited states. Configuration interaction (Cl) and Moller-Plesset (MP) models are two of the most commonly used models of this type. The so-called second-order Moller-Plesset model (MP2) is the most practical and widely employed. It generally provides excellent descriptions of equilibrium geometries and conformations, as well as thermochemistry, including the thermochemistry of reactions where bonds are broken and formed. Discussion is provided in Section n. 

Table 1. Ground state and first excited state configurations, and their energy difference, for lanthanides and actinides...

I),2 (ground state configuration) —— (J), (J)2I (excited state configuration)... 

Consult the molecular orbital diagram in Fig. 6.16 and predict whether BHj will be linear or bent. What would you predict for the excited state configuration, 2[Pg.672]

Investigations of the electronic structure of quadruply bound dimers have relied heavily on electronic spectra to reveal the nature of the excited-state configurations. The availability of quantitative molecular orbital calculations coupled with single-crystal polarized electronic absorption spectral studies of quadruply bound dimers at low temperature has firmly established certain features of the excited electronic states of these compounds. A discussion of electronic spectra follows and a tabulation of energies associated with 6 - 6 transitions in quadruply bound dimers is given in Table 111. 

The existence of a stable 02 molecular ion has been known for some time, and various experimental studies have been carried out to define the electron affinity and structure of the ground electronic state.71-74 Relatively little is known about the excited electronic states of this ion. Bates and Massey75 proposed that several excited state configurations, in addition to the X2ng ground state, should be stable. Boness et al.76 suggested... 

Ab initio calculations for the ground- and several excited-state configurations have been reported by Michels" and Krauss et al.79 These early calculations indicated a large number of bound excited states, particularly of quartet symmetry, arising from the ground 3P+2P dissociation limits for... 

A d2 complex ion has D4 symmetry. It has the electronic configuration (b2)2 in the ground-state and excited-state configurations b2e, b2a, b2b. Determine the electronic states that arise from these configurations. Hence decide which of the possible El transitions from the ground state to excited states are spin- and symmetry-allowed. If any of the possible spin-allowed El transitions are symmetry-forbidden, are they allowed Ml transitions ... 

The energy level structure of an s2 ion is simple [5,6], The s2 ground state configuration yields one level, viz. 1S0. The excited-state configuration, sp, yields the following levels in sequence of increasing energy 3P0, 3P1, 3P2 and lPt (see... 

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