Exponential multiplicity of inherent structures

The mechanically stable spatial arrangements of interacting molecules (pote ntial energy minima, "inherent structures") provide a discrete fiducial bas is for understanding condensed phase properties. Simple plausibility argume nts have been advanced previously suggesting that at fixed positive density the number of distinguishable inherent structures rises exponentially with system size. A more systematic analysis is presented here, using lower and upper bounds, that leads to the same conclusion. Further examination revea ls that the characteristic exponential rise rate for inherent structure enu meration diverges as the density approaches zero, when attractive interpart icle forces are present. [S1063-651X(99)07001-4].