 # [lammps-users] How to calculate effective interaction of two charged molecules

Dear All,

I want to know how to calculate effective interaction between charged molecule one and charged molecule two in LJ liquid (coursed gained model ) solution with counterions.

The distance of two molecules is R. I want to know the effective interaction of two molecules effected by counterions and water molecules in solution.

It is not the question of LAMMPS ,but any sugesstions is highly appreciated

wende

You can hold each of the 2 molecules fixed (e.g. their
center-of-mass fixed) and compute the force on each, which
would be due to the other molecule, solution, etc. Then
you could vary the distance of separation and repeat.

Steve

Dear Steve,

Thanks very much for your reply. This email is for checking my understanding and how to calculate in LAMMPS.

If there are three group A, S(containing solution and ions), A’ in my simulationsystem, I want to calculate effective interaction between group A and A’.

For group A, there are three force(one internal force, two outside force) A<–A, A<–S, A<—A’. The force of A–A is zero, So I could get the effective force( ef_A) between A and other group using 【compute 1 A reduce sum fx fy fz】.

I could get the mean effective interaction(ef_AA’) between A and A’ using the equation ef_AA’ = < |ef_A - ef_A’| >. DOES I get a right understanding? Any suggestions?