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Atomistic
simulations alone are not yet capable of accessing the wide range of
length and time scales needed to understand many soft matter systems
(e.g. colloidal and micellar solutions, protein and polymer
solutions, ionic liquids, etc.). A current challenge is to coarse
grain such systems by developing definitions of effective potentials
that can be determined from atomistic simulations (e.g. molecular
dynamics), and then used in mesoscale simulations which can access
these long time and length scales. A variety of methods, ranging
from the use of purely empirical ad hoc potentials, to use of
effective potentials that rigorously match the partition function,
have been proposed. My current research focuses on three of the most
promising of these approaches:
1).
The well-known iterative Boltzmann procedure proposed by
Soper [1].
2).
A force-matching approach first proposed by Ercolessi and
Adams[2] and later reformulated by Izvekov, et.al. [3].
3).
A rigorous method developed by
Dijkstra, et.al. [4], in which the effective potential is
defined by matching the partition function of the coarse-grained
system to the partition function of the atomistic system.
My
research seeks to understand how the accuracy of coarse-grained
potentials obtained using each of the above approaches is affected
by such parameters as temperature, density, chemical potential of
the solvent, and system size with the long-term goal of developing
guidelines for computing accurate coarse-grained potentials from
atomistic simulations.
[1] "Empirical potential
Monte Carlo
simulation of fluid structure," Soper,
A.K, Chem. Phys., 202 (2-3), 295-306(1996).
[2] "Interatomic potentials from 1st-principles calculations -
the force-matching method," Ercolessi,
F. and J.B. Adams., Europhys. Lett.,
26 (8), 583 - 588 (1994).
[3] "Effective force fields for condensed phase systems
from ab initio molecular dynamics simulation: A new method for
force-matching," Izvekov, S., Parrinello,
M., Burnham, C.J., and G.A. Voth, J.
Chem. Phys., 120 (23), 10896-10913 (2004).
[4]
"Phase diagram of highly asymmetric binary hard-sphere
mixtures", M. Dijkstra, R.
van Roij, and R. Evans. Phys. Rev. E., 59, 5744-5771 (1999).
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