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University of Nebraska - Lincoln

Gordon Gallup Publications

1977

Articles 1 - 2 of 2

Full-Text Articles in Physics

Theory And Applications Of An Atoms In Molecules Approach To The Xα -Scf Method, J. Tylicki, R.J. Hood, Gordon A. Gallup, C.J. Eckhardt Apr 1977

Theory And Applications Of An Atoms In Molecules Approach To The Xα -Scf Method, J. Tylicki, R.J. Hood, Gordon A. Gallup, C.J. Eckhardt

Gordon Gallup Publications

We have studied the Xα -SCF problem with an atoms in molecules approach. LCAO-molecular orbitals are used and the molecular charge and exchange densities are built up from atomic contributions. We have applied our method to CH3F with subsequent comparison to ab initio calculations. The Xα -SCF dipole moment of CH3F is 1.76 D compared with an experimental value of 1.79 D. We also give calculations of TCNQ and TTF with comparisons to recent Xα calculations using the overlapping sphere modification of a muffin-tin potential. Quadrupole moments for TCNQ and TTF have also been determined. The …


Electron Tunneling, Charge Transfer, And The Intermolecular Forces Between Two H2 Molecules, Gordon A. Gallup Mar 1977

Electron Tunneling, Charge Transfer, And The Intermolecular Forces Between Two H2 Molecules, Gordon A. Gallup

Gordon Gallup Publications

The spherically averaged van der Waals potential for the system H2–H2 has been calculated using a nonorthogonal CI method based on SCF orbitals for the individual molecules. With suitable restrictions on the CI calculation we have isolated various contributions to the van der Waals potential, and have found that charge transfer and dispersion effects are comparable to distances corresponding to the potential minimum. The charge transfer contribution is further discussed in terms of a mechanism involving electron tunneling through the intervening space between the molecules. Our calculation gives a spherically averaged van der Waals well depth of …