[gmx-users] short and long range coulomb with pme

[nicolis at guideo.fr]

Hello,
I simulate a CA2+ in a 3 nm SPC water box with pme (actually in different box sizes to see the effect on free energy) without any counter ion.
When I check the interactions with g_energy I get constant 0 for the LR coulomb interactions for CA-CA, CA-SOL and SOL-SOL, but I get a value for the total LR_Coulomb.
If I check the SR Coulomb or the LJ, I get the totals equal to the sum of the CA-CA, CA-SOL and SOL-SOL contributions.
Why this is not the case for LR coulomb? Am I missing soemthing about the parameters rlist and rcoulomb? Should I give a value to rcoulomb-switch?

Thank you,
Yiannis

Here is the output of g_energy:

Energy                      Average       RMSD     Fluct.      Drift  Tot-Drift
-------------------------------------------------------------------------------
LJ (SR)                     6313.15    157.943    157.918 -0.0670855    -9.8617
Coulomb (SR)               -42713.7    277.928     247.32    2.98795    439.234
Coulomb (LR)               -1602.46     121.67    9.01607    2.85928     420.32
Coul-SR:CA-CA                     0          0          0          0          0
LJ:CA-CA                          0          0          0          0          0
Coul-LR:CA-CA                     0          0          0          0          0
Coul-SR:CA-SOL             -1076.75     248.77    38.4408    5.79186    851.415
LJ:CA-SOL                   81.3924    21.6135    15.8288   -0.34681   -50.9818
Coul-LR:CA-SOL                    0          0          0          0          0
Coul-SR:SOL-SOL              -41637    244.734    213.862   -2.80391    -412.18
LJ:SOL-SOL                  6231.76    156.003    155.551   0.279725    41.1201
Coul-LR:SOL-SOL                   0          0          0          0          0