[gmx-users] ERROR IN GROMPP

[Subashini .K]

Hi gromacs users,


I got an error when the following command


 gmx grompp -f em.mdp -c complex_GMX.gro -p complex_GMX.top -o em


The corresponding em.mdp was

; to test
; grompp -f em.mdp -c test_GMX.gro -p test_GMX.top -o em.tpr -v
; mdrun -v -deffnm em
 #Grompp minimization
integrator = steep
nsteps = 500
nstlist = 10
energy-grps = receptor LIG
cutoff-scheme = verlet
vdw-type = cut-off
rvdw = 1.0
coulombtype = pme
rcoulomb = 1.0


The fatal error was


(1) Group receptor referenced in the .mdp file was not found in the index file.
Group names must match either [moleculetype] names or custom index group
names, in which case you must supply an index file to the '-n' option
of grompp.


and

NOTE 1 [file complex_GMX.top, line 77775]:
  System has non-zero total charge: -0.000243
  Total charge should normally be an integer.




The previous commands were


source leaprc.ff14SB
loadAmberParams frcmod.tip4pew
loadAmberParams frcmod.ionsjc_tip4pew
source leaprc.gaff
LIG = loadmol2 LIG.mol2
loadamberparams LIG.frcmod
check LIG
receptor = loadPDB rec_final.pdb
complex = combine {receptor LIG}
set default PBRadii mbondi2
saveAmberParm LIG LIG.top LIG.crd
receptor = loadPDB rec_final.pdb
saveAmberParm receptor rec.top rec.crd
saveAmberParm complex com.top com.crd
savepdb complex complex_gas.pdb
charge complex
addIons2 complex Na+ 0
solvateBox complex TIP4PBOX 10.0
saveAmberParm complex com_solvated.top com_solvated.crd
savepdb complex com_solvated.pdb
quit


How can I fix the error? Please help.

The protein was rec.pdb and
ligand was lig.mol2

What should be energy-grps = ??


Thanks,
Subashini.K