Exists the option of using a tabulated three-body potential (non-bonded)?

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1

Dear Lammps-community,

I am using lammps-7Dec15 but my concern is more general. I was wondering if Lammps is able to handle a tabulated three-body potential in dependency of the angle between triplets of particles jik. Additionally it would be good to consider such triplets just if the distance r_ij < r_cut and r_ik < r_cut (particle i the the central one).
The potential I would like to tabulate has the flavor of the three-body term of the Stillinger-Weber potential but not exactly. As a first step using a tabulated potential with respect to the angle would be more than sufficient. Do you think that is possible with Lammps?

Unless I did not understand correctly the angle_style table accounts exclusively for bonded particles. Sorry if I misunderstood and many thanks for your help.

Kind regards,
Markus

2

Anything is possible if you are willing to write new code to do it.

There are tabulated angle potentials in LAMMPS (angle_style table),

but that is applied to a set of enumerated angle terms. What

you are asking is for a many-body pair potential which will

on-the-fly enumerate all current 3-body terms and apply a tabulated

potential to them (in addition to a pairwise term?). Nothing

exists in LAMMPS currently like that. You can look at

pair polymorphic which may be a generalization of what you

are looking for. If you want to provide the actual tabulated

values in a file, I think you would have to write a new pair style,

e.g. starting with pair sw or pair tersoff and replace the 3-body

analytic methods with something that interpolated from a stored

table.

Sounds like a useful potential, so if you code it up, please contribute

it to LAMMPS.

Steve