supercell and potential energy

Hi all,

I am modelling a molecular crystals using amber gaff. While I minimizing using a unit cell containing 152 atoms, it gave me positive potential enery (somewhere near 1200 with units real). However, when I constructed the supercell 5X5X5 using replicate command and perform minimization, it ended up negative potential energy, which is in stable state.

Is this a normal phenomena? Like finite size effect?

min

Hi all,

I am modelling a molecular crystals using amber gaff. While I
minimizing using a unit cell containing 152 atoms, it gave me positive
potential enery (somewhere near 1200 with units real). However, when I
constructed the supercell 5X5X5 using replicate command and perform
minimization, it ended up negative potential energy, which is in
stable state.

Is this a normal phenomena? Like finite size effect?

no.

axel.