[lammps-users] Bond energy

Dear all,

In the simplest case below for a lj system of 2 and 3 beads, the bond energy comes out to be unusual at the initial configuration (separation=1.0, eql. bond distance=0.75 and K=140).

When there are 2 beads connected with a single bond the bond energy is correctly calculated as 4.375, while adding another bead (2 same type of bonds) it turns out to be 5.833. I would expect the bond energy to double.

I have the 1Oct-06 version with all packages but poems installed.

Any suggestions?


<<in.test>> <<data.2beads>> <<data.3beads>>

in.test (393 Bytes)

data.2beads (499 Bytes)

data.3beads (570 Bytes)

I think that the reported energies are divided by the number of atoms in the
system. Using your parameters, a single bond has an energy of 8.75, so for
the 2 particle system LAMMPS reports 8.75/2 = 4.375. For the 3 particle
system the bond energy is 2*8.75/3 = 5.833.

Hope this helps,