[lammps-users] question about angle_coeff

Dear users and developlers,

I’m trying to describe the interaction of a system with 3 atoms types using three body potentials, but I got confused how to specify the parameters:

for example, if I want to use “cosine/squared” form to describe the 1-2-3 interaction which has atom type 2 in the center:

1
/
2

3

should I try something similar to :

angle_style cosine/squared
angle_coeff 1 2 3 75.0 100.0

? Thanks a lot!

2008/7/24 Bo Qiu <[email protected]…24…>:

Dear users and developlers,

I’m trying to describe the interaction of a system with 3 atoms types using three body potentials, but I got confused how to specify the parameters:

for example, if I want to use “cosine/squared” form to describe the 1-2-3 interaction which has atom type 2 in the center:

1
/
2

3

should I try something similar to :

angle_style cosine/squared
angle_coeff 1 2 3 75.0 100.0

Bo:

You need to read the description of angle coefficients from the documentation:

http://lammps.sandia.gov/doc/angle_coeff.html

You define an angle “type” (which corresponds to the three types of atoms in the specific 1-2-3, or 3-2-1, order you have above); you don’t give all three atom types in the command.

–AEI

The atoms in the angle go in the data file in the Angles section.
See bench/in.rhodo and data.rhodo for an example of how
angles and their potentials are specified.

Steve