[lammps-users] 1-5 LJ interactions

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1

Dear lammps-users

This is a very specific question regarding LJ interactions in a long molecule.
Is it possible to define different set of LJ parameters for atoms
separated by 4 bonds (a 1-5 interaction) ?

Am I correct in the assuming that the special_bonds directive can do
so for 1-2,1-3 and 1-4 interactions, and these interactions cannot be
stronger than the other LJ interactions (coeff <= 1)?.

example:
for 1-4 and 1-5 interactions I have sigma_ij=2.3A epsi_ij=0.3193 kJ/mol
for all other interactions >1-5 sigma_ij=2.5A epsi_ij=0.1849 kJ/mol

Thanks!
Manish Agarwal
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2

Dear lammps-users

This is a very specific question regarding LJ interactions in a long molecule.
Is it possible to define different set of LJ parameters for atoms
separated by 4 bonds (a 1-5 interaction) ?

no. this would require changes to the source code,
particularly the neighborlist code.

Am I correct in the assuming that the special_bonds directive can do
so for 1-2,1-3 and 1-4 interactions, and these interactions cannot be
stronger than the other LJ interactions (coeff <= 1)?.

yes. there is a test that bounds these factors to be within
the range 0.0 to 1.0.

axel.