Ab initio calculations were performed on systems containing various basic ${pi}$ fragments and glycines to generalize the ${pi}$-nonbonded interaction (${pi}$-NBI) method of determining relative conformational and configurational stability of organic molecules. It was found that the relative stability of conformational isomers can be determined in general by the simple application of the ${pi}$-NBI method, but the method is not applicable to the geometrical isomerism in which stronger structural factors are involved. The ${pi}$-NBI effect of a crowded ${pi}$-structure ($n{pi}/m$) is maximum for the system in which n is equal to m. In crowded structures containing heteroatoms, ${P^{pi}}_{ij}$ values of 4N+1 system may become negative, but this sign reversal does not invalidate the predictions based on the ${pi}$-NBI method.