[ESPResSo] Questions about Thermostat

[Lorenzo Isella]

Dear All,
I have been using Espresso to simulate the process of soot
nanoparticles agglomeration (so, strictly speaking, NOT for molecular
dynamics) in a quiescent fluid.
So far I have used the Langevin thermostat to account for collisions
between fluid molecules and nanoparticles.
I really have two separate questions for the list.
(1) What is exactly the effect of having the rotation feature enabled
in the configuration file? In what sense does it modify the Langevin
thermostat?
(2) In the simulations I ran, I start with a certain number of
monomers (i.e. the initial particles I place in the computational box)
which stick upon collisions thus giving rise to aggregates.
The diffusion coefficient of the resulting aggregate does not take
into account the fact that a monomer deep inside the aggregate is
"screened" by the surrounding monomers and hence feels a different
noise with respect to a "free" Brownian monomer.
I wonder whether the DPD thermostat in Espresso can somehow account
for that, but I am not sure it is a reasonable choice and would like
to know the opinion of someone on this list.

Many thanks

Lorenzo