Multiscale modeling in soft matter physics:
Advances
and problems in bridging the time- and length-scale
gap
Mikko Karttunen, Laskennallisen tenkiikan laboratorio
Mesoscopic phenomena in soft matter and biological systems,
e.g. colloids and biomembranes, generally involve some form of coupling
between different characteristic time- and length-scales. Computational
modeling of such multi-scale effects requires new methodology applicable
beyond the realm of traditional techniques such as ab initio and classical
molecular dynamics. In this talk I present a promising coarse-graining
strategy for linking micro- and mesoscales in soft matter and biological
systems. The approach is based on effective pairwise interaction potentials
obtained from detailed atomistic molecular dynamics (MD) simulations, which
are then used in coarse-grained dissipative particle dynamics simulations
(DPD). A simple aqueous NaCl solution is used as a test case. With the
same computational effort we are able to simulate systems of at least one
order of magnitude larger as compared to the MD simulations. The results
from the MD and DPD simulations are found to be in excellent agreement.
In the second part of my talk, I will discuss some of
the challenges related to coarse graining biological systems and some caveats
related to the underlying molecular dynamics simulations. MD simulations
of fully hydrated pure dipalmitoylphosphatidylcholine (DPPC) bilayer are
used as an example.