[lammps-users] mix potentials

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1

HI All,

I am trying to implement a potential that the repulsive part and attractive parts have different functionality. For example, the repulsive part has a very soft potential that takes the form A*r^3+B*r^2+C*r+D, while attractive part takes a lj 7/3 potentails with a shift distance R. How do I implement this kind of mixed pairwise potential in LAMMPS. Your inputs are highly appreciated. Many thanks in advance here.

Shihai

2

HI All,

I am trying to implement a potential that the repulsive part and
attractive parts have different functionality. For example, the
repulsive part has a very soft potential that takes the form
A*r^3+B*r^2+C*r+D, while attractive part takes a lj 7/3 potentails
with a shift distance R. How do I implement this kind of mixed
pairwise potential in LAMMPS. Your inputs are highly appreciated.

well, you can tabulate it or just add another pair potential for that
interaction. the lammps manual documents this process well and lammps
is the one code where it is about as easy as it gets to add a new
potential. just pick one that is reasonably similar. rename the
classes and files and program away.

cheers,
   axel.

3

Axel,

Thanks. I am a new bee to lammps. Would you please enlighten me with a little details such as which documents I should look at to construct a new potential? Or which existing potential is similar to what I am interested.

Shihai

4

Axel,

Thanks. I am a new bee to lammps. Would you please enlighten me with a
little details such as which documents I should look at to construct a new
potential? Or which existing potential is similar to what I am interested.

...should read you a bedtime story as well? :wink:

seriously, please _read_ the lammps documentation.
you can also download it as a pdf and print it out.
take your time. it is well organized, it is worth it,
and it will answer more questions that you can imagine now.

everybody understands that things are confusing at the
beginning, but if you want somebody else to do your homework
for you, you will have to provide compensation for it...

cheers,
    axel.