We present a comparative study of two computer simulation methods to obtain
static and dynamic properties of dilute polymer solutions. The first approach
is a recently established hybrid algorithm based upon dissipative coupling
between Molecular Dynamics and lattice Boltzmann (LB), while the second is
standard Brownian Dynamics (BD) with fluctuating hydrodynamic interactions.
Applying these methods to the same physical system (a single polymer chain in a
good solvent in thermal equilibrium) allows us to draw a detailed and
quantitative comparison in terms of both accuracy and efficiency. It is found
that the static conformations of the LB model are distorted when the box length
L is too small compared to the chain size. Furthermore, some dynamic properties
of the LB model are subject to an L−1 finite size effect, while the BD
model directly reproduces the asymptotic L→∞ behavior. Apart from
these finite size effects, it is also found that in order to obtain the correct
dynamic properties for the LB simulations, it is crucial to properly thermalize
all the kinetic modes. Only in this case, the results are in excellent
agreement with each other, as expected. Moreover, Brownian Dynamics is found to
be much more efficient than lattice Boltzmann as long as the degree of
polymerization is not excessively large.Comment: 11 figures, submitted to J. Chem. Phy