Dear all:
I have a basic question about lammps. I read some lammps website, and I can see that it is capable of running simulations on complicated liquids, some gases like argon, and some solids like copper or SiO2. I am really wondering why lammps can run simulations for so diverse kind of systems since in doing MD simulations, usually we would consider simulating a liquid system as the Allen & Tildesley book said. Could that relate to the diverse kinds of system it could set up? For example, for complicated liquids, the atom_style can be set up as full, but for gas or solid like SiO2, the atom_style is set up as atom. Thanks a lot.
Best,
Laura
2011/9/8 zhangliqun <[email protected]...>:
Dear all:
I have a basic question about lammps. I read some lammps website, and I can
see that it is capable of running simulations on complicated liquids, some
gases like argon, and some solids like copper or SiO2. I am really wondering
why lammps can run simulations for so diverse kind of systems since in doing
MD simulations, usually we would consider simulating a liquid system as the
dear laura,
the main reason for that is, that lammps supports a
very large number of different types of potentials and
functional forms. most MD codes are optimized to
just run a specific set of potentials or problems. that
allows the programmer to add more optimizations
and make more assumptions about the system.
Allen & Tildesley book said. Could that relate to the diverse kinds of
system it could set up? For example, for complicated liquids, the atom_style
can be set up as full, but for gas or solid like SiO2, the atom_style is set
up as atom. Thanks a lot.
the second reason is that it makes smart use of features
of the c++ programming language, that allow to implement
an abstract foundation that takes care of most of the data
management and parallelization issues, while having the
implemented physics fairly separated.
the final reason is, that a _lot_ of people have contributed
to the code over time. this benefits from the previous point,
but still is worth noting, since many have taken the existing
"infrastructure" of lammps and added features to it that went
beyond the initial expectations of what could be done.
that being said, even with a very minimal code, like the
example LJ code described in the allen and tildesley book,
you can do simulations of very different systems and problems.
it just so happens, that both authors are experts in the
simulation of liquids (hence the title). 
cheers,
axel.
Hi, Axel:
Thank you very much for your explanation. It is really amazing that lammps is so capable. Since it can simulation both liquid and solid, it should be able to work on solid/liquid interface. Is there any good forcefield for simulating the organic compound and silica (SiO2) interface? Thank you very much.
Best,
Laura
2011/9/8 zhangliqun <[email protected]...>:
Hi, Axel:
hi laura,
Thank you very much for your explanation. It is really amazing that lammps
is so capable. Since it can simulation both liquid and solid, it should be
able to work on solid/liquid interface. Is there any good forcefield for
absolutely. it has been done a lot with lammps.
check out the list of publications that reference
lammps: LAMMPS Molecular Dynamics Simulator
simulating the organic compound and silica (SiO2) interface? Thank you very
the best way to deal with that, is to look for publications
where people have already done such a simulation with
similar compounds. this need not have used lammps,
there are other software packages that are similarly
capable of running such simulations. the biggest challenge
for such a multi-component system is to find potential
parameters that describe the interactions between
the two different components. please note, that
lammps can also combine multiple types of potentials
through mechanical coupling via the hybrid pair style.
this is likely needed for your setup.
i personally cannot recommend any specific parameter set
or potential type that is best. i would also recommend to
start by first studying each of the two components separately.
so that you get a better feeling for what works well for each
part, before you put them into contact.
cheers,
axel.