The topology of the Ehrenfest force density revisited. A different perspective based on Slater-type orbitals.

The topology of the Ehrenfest force density was studied with Slater-type orbitals (STO). At larger distances from the nuclei, STOs generate similar artefacts as noticed before with Gaussian-type orbitals. The topology of the Ehrenfest force density was found to be mainly homeomorphic with the topology of the electron density. For the first time, reliable integrations of several properties over force density atomic basins were performed successfully. Integration of the electron density of a number of hydrides, fluorides, and chlorides of first row elements over force density basins indicate substantial differences between the partial charges of the atoms as compared with those obtained from electron density basins. Calculations on saturated hydrocarbons confirm that the electronegativity of carbon atoms increases with increasing geometrical strain. Atomic interaction lines are observed to exist in the Ehrenfest force density between the hydrogen atoms of several so-called "congested" molecules, and also in some inclusion complexes of alkanes with helium. However, interaction lines are lacking in several other controversial cases.