Reviews in Computational Chemistry Volume 18

134 Polarizability in Computer Simulations
packages, thereby making these methods much more accessible to the nonspecialist.
In particular, we expect polarizable models, and especially polarizable
water models, to become more prevalent in biomolecular simulations involving
heterogeneous solvent environments. Inclusion of polarizability in the
potentials for proteins and other macromolecular systems is also likely to
become more common, and hence a careful assessment of the importance of
polarizability to these systems is needed. Until the importance of polarizability
has been clearly demonstrated, the added computational cost of modeling the
polarization makes it is unlikely that polarizable models will displace more
traditional models for the bulk of routine simulation, particularly when
applied to large systems.
Future directions in the development of polarizable models and simulation
algorithms are sure to include the combination of classical or semiempirical
polarizable models with fully quantum mechanical simulations, and with
empirical reactive potentials. The increasingly frequent application of Car–
Parrinello ab initio simulations methods 156 may also influence the development
of potential models by providing additional data for the validation of
models, perhaps most importantly in terms of the importance of various interactions
(e.g., polarizability, charge transfer, partially covalent hydrogen
bonds, lone-pair-type interactions). It is also likely that we will see continued
work toward better coupling of charge-transfer models (i.e., EE and semiempirical
models) with purely local models of polarization (polarizable dipole
and shell models).
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