For some reason pair LJ cut doesn't match the analytical form for the Lennard Jones potential. Surprisingly, forces from pair_lj_smooth do match the analytical form.
At the point of tangency of the spring and LJ force, we have an inflection point in the energy for particle2. This is also observed from energy minimization runs.
The system has 3 particles, with initial location:
{1}-(0,0) {2}-(1.05,0) {3}-(L,0) ; particles 1&3 are fixed , only 2 can move along x-axis.
Interactions are--> 1-2: Lennard Jones with cutoff at 10.0; 2-3: harmonic force with force proportional to separation between 2 & 3 (see lammps docs for bond_harmonic).
For certain values of L the energy of {2} has 2 minima and 1 maxima , for 1 special value of L (when spring force is a tangent to the LJ force) the energy of {2} has an inflection point and for all bigger values of L there is only 1 minima in the energy of {2}.
For some reason pair LJ cut doesn't match the analytical form for the Lennard Jones potential. Surprisingly, forces from pair_lj_smooth do match the analytical form.
ReplyDeleteAt the point of tangency of the spring and LJ force, we have an inflection point in the energy for particle2. This is also observed from energy minimization runs.
The system has 3 particles, with initial location:
ReplyDelete{1}-(0,0) {2}-(1.05,0) {3}-(L,0) ; particles 1&3 are fixed , only 2 can move along x-axis.
Interactions are--> 1-2: Lennard Jones with cutoff at 10.0; 2-3: harmonic force with force proportional to separation between 2 & 3 (see lammps docs for bond_harmonic).
For certain values of L the energy of {2} has 2 minima and 1 maxima , for 1 special value of L (when spring force is a tangent to the LJ force) the energy of {2} has an inflection point and for all bigger values of L there is only 1 minima in the energy of {2}.