Mulliken neutral

Evaluation of the Work Term from Charge Transfer Spectral Data. The intermolecular interaction leading to the precursor complex in Scheme IV is reminiscent of the electron donor-acceptor or EDA complexes formed between electron donors and acceptors (21). The latter is characterized by the presence of a new absorption band in the electronic spectrum. According to the Mulliken charge transfer (CT) theory for weak EDA complexes, the absorption maximum hv rp corresponds to the vertical (Franck-Condon) transition from the neutral ground state to the polar excited state (22). 

It is also practical to invoke a one-electron approximation in the FCD method [41] when one estimates donor and acceptor charges. Thus, one approximates the fragment charges of the radical cations [(G C),(AT)] and [(GC),(A+T)] via the corresponding Mulliken populations of the HOMO and HOMO-1 of the neutral dimer. Then, the charge on fragment / in [(G+C),(AT)] is... 

This was justified as follows. The energy required to take an electron from a neutral atom Y to a neutral atom Z is /Y — AZt whereas the energy cost to take an electron from a neutral atom Z to a neutral atom Y is Iz — Ay. Hence, the two atoms Y and Z would have an equal propensity for attracting electrons or equal electronegativity if /Y — Az = Iz — AY, that is if IY + Ay = Iz + Az. This is consistent with the Mulliken definition, eqn (3.35), the factor 1/2 being arbitrary. As can be seen by comparing the two different scales in Fig. 3.5, the Mulliken values are approximately 2.8 times the Pauling values. 

Results of the calculations for the TiLn (L=H, Cl, CH3) neutral structures are displayed in Tables 2-4, which provide dissociation energies, bond lengths, Mulliken charges and overlap populations for these compounds. 

The Mulliken population analysis for MF2 and MF4 (M = Hg and 112) [108] suggests that the 6d orbitals of element 112 should be involved in bonding to a larger extent than the 5d orbitals of Hg. The calculated energies of the decomposition reactions MF4 —> MF2 + F2 and MF2 -> M + F2 have confirmed the conclusion that the 4+ oxidation state of element 112 will be accessible and the 2+ state not [12], The neutral state of element 112 should also be more preferred than that of Hg. 

The Mulliken arguments may be extended to charge-transfer crystals. The first solid charge-transfer crystals studied were colored, but had low thermodynamic stability relative to the separate neutral donor and acceptor crystals. However, if the donor D had low ID and if the acceptor had high Aa ... 

E(Z, N) — E(Z, N— 1), that is from an ionization potential. Indeed it has already been seen in Section 7 that, for a neutral atom, n is in magnitude approximately half the ionization potential, for the case when the electron affinity is sufficiently small to be neglected. Mulliken s definition of electronegativity, namely... 

In calculating a theoretical photoelectron spectmm, the atomic ionization cross section a. is usually taken so far from the theoretical values calculated for a neutral free atom in the ground state. However, the MO calculation by DV-Xa method is carried out self consistently and provides Q. by Mulliken population analysis using the SCF MO wave function calculated. In the present calculations, the atomic orbital Xj used for the basis function flexibly expands or contracts according to reorganization of the charge density on the atom in molecule in the self-consistent field. Furthermore, excited state atomic orbitals are sometimes added to extend the basis set. In such a case, the estimation of peak intensity of the photoionization using the data of Oj previously published is not adequate. Thus a calculation of the photoionization cross section is required for the atomic orbital used in the SCF calculation in order... 

The phenomenon was explained by Mulliken in 1952 [168] these 1 1 charge-transfer solution complexes have ground-state wavefunctions >g and excited-state wavefunctions (jtp which are linear combinations of the unperturbed wavefunctions c )q of the neutral donor D and the neutral acceptor A, and of the ionic state wavefunctions ( )ct of the donor cation and the acceptor anion A as follows ... 

These have often been called charge-transfer complexes, but this term implies that the bonding involves charge transfer, which is not always the case, so that the more neutral name EDA complex is preferable. See Mulliken, R.S. Person, W.B. ]. Am. Chem. Soc. 1969, 91, 3409. 

---