[gmx-users] free energy with TIP4P bug fixed

[chris.neale at utoronto.ca]

Since I also use the pull code on these systems (while not using the  
free energy code), I tested that system and verified that, for my  
system, the tip4p-based Coulomb (SR) discrepancy does not appear to  
result when the pull code is used in gromacs 4.0.3.

With pull code and using energygrps = System:

    Energies (kJ/mol)
           Angle    Proper Dih. Ryckaert-Bell.          LJ-14     Coulomb-14
     1.45925e+03    5.76366e+02    5.07995e+02    7.02412e+02    6.05631e+03
         LJ (SR)        LJ (LR)  Disper. corr.   Coulomb (SR)   Coul. recip.
     2.89037e+05   -6.95173e+03   -2.44860e+03   -1.91197e+06   -2.16432e+05
    COM Pull En.      Potential    Kinetic En.   Total Energy    Temperature
     3.39203e+02   -1.83913e+06    5.96331e+03   -1.83316e+06    6.77985e+00

Without pull code and using energygrps = System:

    Energies (kJ/mol)
           Angle    Proper Dih. Ryckaert-Bell.          LJ-14     Coulomb-14
     1.45925e+03    5.76366e+02    5.07995e+02    7.02412e+02    6.05631e+03
         LJ (SR)        LJ (LR)  Disper. corr.   Coulomb (SR)   Coul. recip.
     2.89037e+05   -6.95173e+03   -2.44860e+03   -1.91197e+06   -2.16432e+05
       Potential    Kinetic En.   Total Energy    Temperature Pressure (bar)
    -1.83947e+06    5.96331e+03   -1.83350e+06    6.77986e+00   -1.05997e+04

Without pull code and using energygrps = DPC SOL:

    Energies (kJ/mol)
           Angle    Proper Dih. Ryckaert-Bell.          LJ-14     Coulomb-14
     1.45925e+03    5.76366e+02    5.07995e+02    7.02412e+02    6.05631e+03
         LJ (SR)        LJ (LR)  Disper. corr.   Coulomb (SR)   Coul. recip.
     2.89037e+05   -6.95171e+03   -2.44860e+03   -1.91197e+06   -2.16432e+05
       Potential    Kinetic En.   Total Energy    Temperature Pressure (bar)
    -1.83947e+06    5.96332e+03   -1.83350e+06    6.77986e+00   -1.05997e+04

Chris.