Molecular orbital theory for

In our previous discussions on Hj, we saw that the lone electron occupies the a s molecular orbital  

The molecular orbital theory was first introduced by F. Hund (of the Hund s rule fame) and R. S. Mullikan, with the latter winning the Nobel Prize in chemistry in 1966. Since cris can accommodate two electrons, in molecular orbital theory, the wavefunction for H2 is 

From this function, we can see that both electrons in H2 reside in the ellipsoidal cris orbital. This situation is similar to that of the helium atom, where both 

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Streitwieser, A., 1961. Molecular Orbital Theory for Chemists. Wiley, New York. 

W. T. Borden, Modem Molecular Orbital Theory for Organic Chemists, Prentice-Hall, Englewood Cliffs, New Jersey, 1975. 

Hiickel s calculations on planar conjugated systems were extensively exploited, and I refer you once again to Streitwieser s classic book. Molecular Orbital Theory for Organic Chemists. What few calculations that had been done at that time on the (T framework had used the method of linear combination of bond orbitals. 

Towards a Systematic Molecular Orbital Theory for Excited States James B. Foresman, Martin Head-Gordon, John A. Pople and Michael J. Frisch... 

PMO Theory of Organic Chemistry Plenum NY, 1975 Zimmerman, H.E. Quantum Mechanics for Organic Chemists Academic Press NY, 1975 Borden, W.T. Modem Molecular Orbital Theory for Organic Chemists Prentice-Hall Englewood Cliffs, NJ, 1975 Dewar, M.J.S. The Molecular Orbital Theory of Organic Chemistry McGraw-Hill NY, 1969 Liberies, A. Introduction to Molecular Orbital Theory Holt, Rinehart, and Winston NY, 1966. 

There are other methods. For a discussion of the free-electron method, see Streitwieser Jr., A. Molecular Orbital Theory for Organic Chemists Wiley NY, 1961, p. 27. For the nonpairing method, in which benzene is represented as having three electrons between adjacent carbons, see Hirst, D.M. Linnett, J.W. J. Chem. Soc., 1962,1035 Firestone, R.A. J. Org. Chem., 1969, 34, 2621. 

Streitwieser, A.,Jr. Molecular Orbital Theory for Organic Chemists John Wiley New York, 1961, p. 135. 

Figure 6.8. Summary of molecular orbital theory for homonuclear molecules. Note how the stability of a chemical bond depends both on the interaction strength and the filling of the orbitals.

Serrano-Andres, L., Merchan, M., Nebot-Gil, I., Lindh, R., Roos, B. O., 1993, Towards an Accurate Molecular Orbital Theory for Excited States Ethene, Butadiene, and Hexatriene , J. Chem. Phys., 98, 3151. 

The limitation of the above analysis to the case of homonuclear diatomic molecules was made by imposing the relation Haa = Hbb> as in this case the two nuclei are identical. More generally, Haa and for heteronuclear diatomic molecules Eq. (134) cannot be simplified (see problem 25). However, the polarity of the bond can be estimated in this case. The reader is referred to specialized texts on molecular orbital theory for a development of this application. 

Streitwieser, Jr., A. Molecular Orbital Theory for Organic Chemists. New York John Wiley Sons, Inc. 1961. 

How well can continuum solvation models distinguish changes in one or another of these solvent properties This is illustrated in Table 2, which compares solvation energies for three representative solutes in eight test solvents. Three of the test solvents are those shown in Table 1, one is water, and the other four were selected to provide useful comparisons on the basis of their solvent descriptors, which are shown in Table 3. Notice that all four solvents in Table 3 have no acidity, which makes them more suitable, in this respect, than 1-octanol or chloroform for modeling biomembranes. Table 2 shows that the SM5.2R model, with gas-phase geometries and semiempirical molecular orbital theory for the wave function, does very well indeed in reproducing all the trends in the data. 

Stock, L. M., and Brown, H. C. (1963) in Adv ices in Physical Organic Chemistry, Volume 1, ed. V. Gold, Academic Press, London and New York, p. 35. Streitwieser, A. Jr., (1961). Molecular Orbital Theory for Organic Chemists , John Wiley, New York. 

The Fermi surface plays an important role in the theory of metals. It is defined by the reciprocal-space wavevectors of the electrons with largest kinetic energy, and is the highest occupied molecular orbital (HOMO) in molecular orbital theory. For a free electron gas, the Fermi surface is spherical, that is, the kinetic energy of the electrons is only dependent on the magnitude, not on the direction of the wavevector. In a free electron gas the electrons are completely delocalized and will not contribute to the intensity of the Bragg reflections. As a result, an accurate scale factor may not be obtainable from a least-squares refinement with neutral atom scattering factors. 

Fenske, R. F. Semi-empirical molecular-orbital theory for transition-metal complexes. Inorg. Chem. 4, 33 (1965). 

Ohnishi, S., and Tsukada, M. (1989). Molecular orbital theory for scanning tunneling microscopy. Solid State Commun. 71, 391-394. 

Foresman,. 1. B., Head-Gordon, M., Pople, J. A., and Frisch, M. 1992. Toward a Systematic Molecular Orbital Theory for Excited States J. Phys. Chem., 96, 135. 

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