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[lammps-users] CHARMM force field
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[lammps-users] CHARMM force field


From: neda Sanchuli <n.sanchuli@...16...>
Date: Mon, 23 Oct 2017 16:22:57 +0000 (UTC)

Dear all,

I want to simulate heptan with CHARMM36 force field. I checked the bonded and non-bonded parameters files of this force field.
Heptan has 7 types dihedrals, two dihedrals of them have several parameters:


V(dihedral) = K(1 + cos(n(phi) - delta))

 [ dihedraltypes ]
 i                j              k            l                 delta          K             n
CC32A    CC32A    CC32A    CC32A       0.000000     0.470742     5
CC32A    CC32A    CC32A    CC32A       0.000000     0.395723     4
CC32A    CC32A    CC32A    CC32A      180.000000   0.626554    3
CC32A    CC32A    CC32A    CC32A       0.000000     0.269868     2

The dihedral_style is charmm. How can I choose the parameters and what's the reason?

Thanks.