Problem about interaction potential between polymer and diamond

Hi,dear ones,I plan to run a simulation using Lammps with two materials: PMMA and Diamond.
PMMA is a polymer consists of three elements: Carbon,Hydrogen and Oxygen, and Diamond is formed by Carbon.
However, I wonder if there are suitable interaction potential between polymer and diamond.
Could anyone tell me which potential I can use? and how to determine the potential parameters between Carbon and elements in the polymer? Thanks for reading my question!

Yuan

Hi,dear ones,I plan to run a simulation using Lammps with two materials:
PMMA and Diamond.
PMMA is a polymer consists of three elements: Carbon,Hydrogen and Oxygen,
and Diamond is formed by Carbon.
However, I wonder if there are suitable interaction potential between
polymer and diamond.

that is a question, that is best answered by searching the
published literature than posting to a mailing list.

Could anyone tell me which potential I can use? and how to determine the
potential parameters between Carbon and elements in the polymer? Thanks
for reading my question!

which potential to use is always a tricky question and there is
often no single answer to this. just have a look at how many
potentials have been published to simulate liquid water, and there
(still, after over 30 years) is no consensus about what is the best.

one important issue that you have to keep in mind is, that in
classical models, the element itself is irrelevant. bio force fields
have often many *different* atom types for carbon, hydrogen,
nitrogen and oxygen atoms. those types (and the resulting
parameter sets) depend on the "environment", i.e. are motivated
by the (organic) chemical concept of "functional groups", that is
subgroups that have the same chemical function exhibit such a
similar behavior, that they can be represented by the same set
of parameters.

however, even that is a simplification (e.g. it ignores polarization).

in general, derivation of force field parameters is a complicated
matter and - in many cases - a topic of research on its own. i
suggest you have a more detailed look at that in the relevant
text books and literature.

unless by chance somebody here has done the exact same
system that you would like to simulate and can send you
ready to use inputs, you'll have to do the "legwork" on your
own. regardless, doing a validation of your force field parameters,
i.e. determining whether a choice of parameters is sufficient
to reproduce a system at the desired accuracy is something
that you *always* have to do yourself. no advice from a mailing
list can replace that. what would you write in your paper?
some random person that i don't know told me that this was ok???
:wink:

cheers,
    axel.

Thank you very much, Axel.
I see your point ,and thank you for your advice again.
PS: You are really a lovely and responsible professor.
:wink:

在 2012-11-02 17:43:38,“Axel Kohlmeyer” <[email protected]…24…> 写道: