[gmx-users] Re: Turning off electrostatics between groups using custom tables?

[Smitty]

> 1) That .mdp applies different tables to K-K, protein-protein and all 
> other interactions, which isn't what you've said you've done.
> 3) Your life will be simpler if you use energygrp_table only for the 
> group-group interactions you want to change, and leave the default 
> interactions normal. It will also be faster, because using tabulated 
> interactions is much slower than the normal ones.
> 
> Mark
> -- 
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Thanks mark, I have since gone back and modified the .mdp file after
re-reading the tutorial and manual and have come up with the new attached
.mdp file ( http://gromacs.5086.n6.nabble.com/file/n5000746/md.mdp md.mdp ,
which I think removes the problems you highlighted in 1) and 3). 

I no longer have an exploding system; however, when I run g_energy on the
output .edr file from a short run (looking at the K+ and protein energy
groups) I get the following output:

Energy                      Average       RMSD     Fluct.      Drift 
Tot-Drift
-------------------------------------------------------------------------------
Coul-SR:K+-K+                551.07    208.162    89.6287    0.69831   
650.828
LJ-SR:K+-K+                 1.43168   0.794798   0.668453 0.00159813   
1.48946
Coul-14:K+-K+                     0          0          0          0         
0
LJ-14:K+-K+                       0          0          0          0         
0
Coul-SR:K+-Protein         -6994.99     1978.5    1003.44   -6.33779  
-5906.85
LJ-SR:K+-Protein            52.3447    13.7398    11.2697  0.0292135   
27.2271
Coul-14:K+-Protein                0          0          0          0         
0
LJ-14:K+-Protein                  0          0          0          0         
0
Coul-SR:Protein-Protein    -246.639    43.9503     30.246    0.11852   
110.461
LJ-SR:Protein-Protein      -81.9209    10.2086    9.29929  0.0156543   
14.5899
Coul-14:Protein-Protein     1477.91    19.7693    16.2154 -0.0420325  
-39.1745
LJ-14:Protein-Protein       158.219    11.1455    10.5729 -0.0131077  
-12.2164

Which is closer to what I am going for, but I would expect that the
Coul-14/LJ-14 K+-K+ would not be zero. Any ideas on what I am still not
doing correct? Thanks for all the help.



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