[gmx-users] gmx 3.1.4 vs 3.2.1

[Marcos Villarreal]

Hello,

I am testing gmx 3.1.4 vs 3.2.1. For several  systems, I have calculated  the 
potential energy using the same pdb, topology, compiler, etc. 
When comparing the results,  the Long range part of the LJ energy is the only 
term that varies by a significant amount (about 10%) between the two 
versions. The LR-LJ energies calculated with 3.1.4 are always smaller than 
the calculated with 3.2.1.
When you use a twin-range cutoff of 0.9-1.2 and compare with the results made 
with a single 1.2 nm cutoff, the sum of SR-LJ + LR-LJ of the twin-range only 
coincides with the result of the single cutoff when you use 3.2.1.

Is this indicating that the LR-LJ term is not correctly calculated in gmx 
3.1.4?

Saludos,
                Marcos.