Molecular structure polyatomic linear

Furthermore if we take the free-energy functional as given by Chrmdler et al.° for molecular(polyatomic) liquids, we obtain from (11) a L-D equation for each of the atomic species constituting the molecules, which is very similar to (20). After liniarization as done in (22), we obtain a linear diffusion equation, which was used by Hirata to investigate the dyntunic structure factors of water. 

Since the valence bond theory is insufficient to explain the structure and behavior of polyatomic molecules, the molecular orbital theory was developed. In this theory, it is accepted that electrons in a polyatomic molecule should not be regarded as belonging to particular bonds but should be treated as spreading throughout the entire molecule every electron contributes to the strength of every bond. A molecular orbital is considered to be a linear combination of all the atomic orbitals of all the atoms in the molecule. Quantum... 

The valence-bond treatment of polyatomic molecules is closely tied to chemical ideas of structure. One begins with the atoms that form the molecule and pairs up the unpaired electrons to form chemical bonds. There are usually several ways of pairing up (coupling) the electrons. Each pairing scheme gives a VB structure. A Heitler-London-type function (called a bond eigenfunction) is written for each structure i, and the molecular wave function is taken as a linear combination 2, c,4>, of the bond eigenfunctions. The variation principle is then applied to determine the coefficients c,. The VB wave function is said to be a resonance hybrid of the various structures. 

The probabilities of absorption by structures larger than an atom are determined in essentially the same way. For diatomic and linear polyatomic molecules the orbital momentum selection rule becomes AA = 0, 1, where A is the symbol for molecular total orbital angular momentum. For systems with appropriate symmetry, the rules are g m, -I- <-> H-, —. For non-linear polyatomic molecules... 

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