  Compressing or cooling a fluid typically enhances its static interparticle
correlations. However, there are notable exceptions. Isothermal compression can
reduce the translational order of fluids that exhibit anomalous waterlike
trends in their thermodynamic and transport properties, while isochoric cooling
(or strengthening of attractive interactions) can have a similar effect on
fluids of particles with short-range attractions. Recent simulation studies by
Yan et al. [Phys. Rev. E 76, 051201 (2007)] on the former type of system and
Krekelberg et al. [J. Chem. Phys. 127, 044502 (2007)] on the latter provide
examples where such structural anomalies can be related to specific changes in
second and more distant coordination shells of the radial distribution
function. Here, we confirm the generality of this microscopic picture through
analysis, via molecular simulation and integral equation theory, of
coordination shell contributions to the two-body excess entropy for several
related model fluids which incorporate different levels of molecular
resolution. The results suggest that integral equation theory can be an
effective and computationally inexpensive first-pass tool for assessing, based
on the pair potential alone, whether new model systems are good candidates for
exhibiting structural (and hence thermodynamic and transport) anomalies.
