Hydrogen fluoride molecular orbitals

S. G. Anderson and D. P. Santry, J. Chem. Phys., 74, 5780 (1981). Nonempirical Molecular Orbital Calculations for Hydrogen-Bonded Molecular Solids Molecular Dipole and Quadruple Moments for Solid Hydrogen Fluoride and Hydrogen Chloride. 

FIGURE 10.2 Molecular orbitals in hydrogen fluoride, plotted using two isosurfaces, at 0.02 e 1/2 Bohr 3/2. (See the color version of this figure in Color Plates section.)... 

In 1969, Thomas published two papers [11,12] in which a molecular structure theory was developed without invoking the Bom-Oppenheimer approximation. In these publications and two further papers published in 1970 [13,14], Thomas studied methane, ammonia, water and hydrogen fluoride adding the kinetic energy operators of the protons to the electronic hamiltonian and using Slater-type orbitals centered on the heavier nuclei for the protonic wave functions. Over the years, a number of authors [15-23] have attempted the development of a non-Bom-Oppenheimer theory of molecular structure, but problems of accuracy and/or feasibility remain for applications to arbitrary molecular systems. 

In the examples of H2 and hydrogen fluoride, HF, we have constructed molecular orbitals by taking a linear combination of atomic orbitals—one atomic orbital being used for each atom. In H2, for example, we combined the Is orbital for each atom for HF we used the Is orbital of hydrogen and the 2p orbital of fluorine. However, sometimes this is not satisfactory and we must use two or more orbitals from a given atom. 

Show how a hydrogen I5 atomic orbital and a fluorine 2p atomic orbital overlap to form bonding and antibonding molecular orbitals in the hydrogen fluoride molecule. Are these molecular orbitals a- or tt molecular orbitals ... 

Figure 1.10. A schematic representation of a few of the molecular orbital energies in hydrogen fluoride (HF). The sigma (o) and pi (ti) bonding relative positions are shown, but only the sigma (o ) antibonding orbital position is provided.

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