And nonbonded repulsions

The analysis of the results concentrated on the time-averaged structure and on correlation functions that illustrate the time-dependence of internal motions. A key conclusion was that the internal motion was fluidlike at ordinary temperatures, i.e. that the dynamics of atomic displacements are dominated by collisions with neighboring atoms, at least on the picosecond time scale. Hence, it is argued, ...many of the dynamical properties (though not necessarily the correct average structure) can be obtained from any potential function which includes the forces that depend strongly upon distance (covalent and hydrogen bonds, nonbonded repulsions) and provides sufficient attractive interactions to preserve the compact structure of the native system. ... 

Thinking along these lines demonstrates that one has lost track of what is a true concept and what is an empirical descriptor. That nonbonded repulsion and attraction are descriptions of two possible modes of operation of nonbonded atoms, with neither being the rule or the exception, is vividly demonstrated by compilations of data pertaining to the relative stability of 1,2 disubstituted ethenes. Depending on whim, one can easily pronounce either nonbonded repulsion or... 

With the above in mind, we can state that the purpose of this paper is to show that there exists an electronic mechanism which is present in the vast majority of organic polyatomic molecules and which, if not overriden by other factors, it causes them to adopt uncrowded" geometries. This mechanism is natural nonbonded repulsion and it is the direct consequence of the fact that ground state organic molecules are (partly or totally) "forbidden" entities, i.e., they are the result of (partly or totally) "forbidden" unions of cores and ligands. 

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