[gmx-users] using nopbc is not equal to using pbc with big box dimensions

[Golshan Hejazi]

Hello,

I would like to compute the energy of a system in vacuum. For this I first computed energy by using nopbc and putting rculomb=rvdw=0 ... 
Then I computed the energy using pbc with a big box dimension (periodic images are separated by a length more than cutoff )... this means that periodic images dont interact ... results are different ... but which one is correct?


Can you help me to understand this better
G.