[lammps-users] question about improper_style harmonic

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1

Dear all:
I am trying to apply "improper" to my simulation. The am using improper_style of harmonic, and from what I know, for harmonic style, I would need angle and K (which is also in units of kcal/mol-rad^2). However, I am currently using Tripos forcefield, and the K value that I have is in kcal/mol-angstrom^2, which is actually in terms of distance instead of an angle. So, I would like to know what needs to be done in order to get the improper term works in distance unit. Thank you so much for your help.

Best wishes,
Yani

2

I'm not familiar with the Tripos formula, but you will need
to convert your K to LAMMPS units if you want to run it in LAMMPS.

Steve

3

Dear Steve:
Thanks for your reply. I have another question. Actually, in order to use the tripos force field, I think I will need to modify the subroutine for improper case and change it to the units that I want. May I know whether there is any documentation that I can look at to know how to modify one of the subroutines in Lammps? Thank you.

Yani