core dump for NLO "gridpack"

Dear Tim,

Is it specific to your process or does it happen for all processes?
Do you use a standard setup or are you running from within another framework?
What cluster type and batching system are you using?
Which version of the code are you using?

Best regards,
Rikkert

Dear Rikkert,
thank you for your quick reply:
I am running MG5_aMC@NLO version 2.2.2 - so the standard setup. The error occurs for the study of p p > t t~ b b~ [QCD]. I tried to generate a NLO gridpack for p p > t t~ [QCD] as a test and that worked fine.
For the question concerning cluster type and batching system I am unsure. I am running on a PBS cluster but I have set the option "single machine" as suggested here ( https://answers.launchpad.net/mg5amcnlo/+question/243268 ).
If you need further information, please let me know.
Best regards,
Tim

Dear Tim,

Are you trying to create the gridpack or are you trying to use it to generate events? The "single machine" option is only for the generating events stage.

Your problem seems to be related to some libraries being not precent or being compiled with a different version of a compiler. Therefore it is rather strange that "p p > t t~ [QCD]" works and "p p > t t~ b b~ [QCD]" doesn't: from the code structure point of view there is no difference between the two. Are you running both on exactly the same machine(s)?

Best,
Rikkert

Dear Rikkert,

sorry for the unclear response. - I am compiling in multi-core mode. I think it is a problem of a wrong/bad interface between mg5_aMC@NLO and Pythia8.
I succeeded in producing/compiling an NLO gridpack for pp > t t~ b b~ [QCD] with Herwig6 as Parton shower. It crashes when I try to produce/compile a gridpack pp > t t~ b b~ [QCD] with Pythia8 as parton shower.
I also have problems with normal aMC@NLO runs. Should I open another thread for this?

Cheers and thank you for your help!
Tim

Dear Tim,

There is no difference in creating an MG5-aMC@NLO gridpack with pythia8 and herwig6 apart from the functional form of the subtraction terms which are all coded up directly in Fortran. Therefore, I don't understand your bug: there is no difference in linking libraries or anything. It makes no sense. (Also I cannot reproduce your problem locally, which makes it extremely difficult for me to investigate).

Can you try pinpointing where the problem might be? Is it only with pythia8? For which processes? Did you try to regenerate the process from scratch? Is it also there with an earlier version of the code?

Best regards,
Rikkert

Dear Rikkert,
thank you for your help.
A first note not related to my question but maybe that is important for you to know:
I am running with Madgraph 2.2.2 and Pythia 8.2. - Apparently there is one known bug and I got new files from Paolo Torrielli (Pythia82.cc and Pythia82_hep.cc). I replaced them with the old files in madgraph_maindir/Template/NLO/MCatNLO/srcPythia8/
The normal full chain now works, i.e. I am able to generate p p > t t~ [QCD] and shower it with Pythia8.2 without any core dumps. - I did this today so previously I encountered the core dump during gridpack production with the standard setup.

I now tried again to run the production of the gridpack for p p > t t~ b b~ [QCD] and it failed (I attach the new error messages below). I tried to generate everything from scratch. - Since I was able to produce a NLO-gridpack with Herwig6 as parton shower for p p > t t~ b b~ [QCD] I suppose it is a problem related to Pythia8.
I am able to produce a p p > t t~ [QCD] gridpack with Pythia8 as parton shower. -
The core dump occurs for p p > t t~ b b~ [QCD] with Pythia8 as parton shower. I didn't try any other processes so I can't tell if I have the problem also for other processes.

I am going to try to generate:
p p > t t~ b b~ [QCD] with MG5_aMC@NLO 2.1.2 + Pythia8.205
p p > t t~ b b~ [QCD] with MG5_aMC@NLO 2.2.2 + Pythia8.186

After having done that I give you further information.

The error I get is the following:
*** glibc detected *** ../madevent_mintMC: double free or corruption (out): 0x0000000012af9060 ***
======= Backtrace: =========
/lib64/libc.so.6[0x3675075e66]
/lib64/libc.so.6[0x36750789b3]
../madevent_mintMC[0x9e3b90]
../madevent_mintMC[0x9e2a75]
../madevent_mintMC[0x9e2095]
../madevent_mintMC[0x9e3fa6]
../madevent_mintMC[0x987a95]
../madevent_mintMC[0x989fd3]
../madevent_mintMC[0x982417]
../madevent_mintMC[0x6326f7]
../madevent_mintMC[0x601b58]
../madevent_mintMC[0x5a7903]
../madevent_mintMC[0x5126e2]
../madevent_mintMC[0x514ec5]
../madevent_mintMC[0x514f12]
../madevent_mintMC[0x4ed436]
../madevent_mintMC[0x4a9acc]
../madevent_mintMC[0x4b31d1]
../madevent_mintMC[0x4f7f6f]
../madevent_mintMC[0x4f2598]
../madevent_mintMC[0x4fad75]
../madevent_mintMC[0x4fe58c]
/lib64/libc.so.6(__libc_start_main+0xfd)[0x367501ed5d]
../madevent_mintMC[0x40a819]
======= Memory map: ========
00400000-00c11000 r-xp 00000000 00:21 21954501 /project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/madevent_mintMC
00e11000-00e58000 rw-p 00811000 00:21 21954501 /project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/madevent_mintMC
00e58000-127f2000 rw-p 00000000 00:00 0
12a71000-12bf7000 rw-p 00000000 00:00 0 [heap]
3674c00000-3674c20000 r-xp 00000000 fd:00 264094 /lib64/ld-2.12.so
3674e1f000-3674e20000 r--p 0001f000 fd:00 264094 /lib64/ld-2.12.so
3674e20000-3674e21000 rw-p 00020000 fd:00 264094 /lib64/ld-2.12.so
3674e21000-3674e22000 rw-p 00000000 00:00 0
3675000000-367518a000 r-xp 00000000 fd:00 285154 /lib64/libc-2.12.so
367518a000-367538a000 ---p 0018a000 fd:00 285154 /lib64/libc-2.12.so
367538a000-367538e000 r--p 0018a000 fd:00 285154 /lib64/libc-2.12.so
367538e000-367538f000 rw-p 0018e000 fd:00 285154 /lib64/libc-2.12.so
367538f000-3675394000 rw-p 00000000 00:00 0
3675400000-3675483000 r-xp 00000000 fd:00 335931 /lib64/libm-2.12.so
3675483000-3675682000 ---p 00083000 fd:00 335931 /lib64/libm-2.12.so
3675682000-3675683000 r--p 00082000 fd:00 335931 /lib64/libm-2.12.so
3675683000-3675684000 rw-p 00083000 fd:00 335931 /lib64/libm-2.12.so
7fadcc099000-7fadcc09e000 rw-p 00000000 00:00 0
7fadcc09e000-7fadcc0d9000 r-xp 00000000 00:1f 48050591 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libquadmath.so.0.0.0
7fadcc0d9000-7fadcc2d8000 ---p 0003b000 00:1f 48050591 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libquadmath.so.0.0.0
7fadcc2d8000-7fadcc2d9000 rw-p 0003a000 00:1f 48050591 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libquadmath.so.0.0.0
7fadcc2d9000-7fadcc2ee000 r-xp 00000000 00:1f 358720 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libgcc_s.so.1
7fadcc2ee000-7fadcc4ee000 ---p 00015000 00:1f 358720 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libgcc_s.so.1
7fadcc4ee000-7fadcc4ef000 rw-p 00015000 00:1f 358720 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libgcc_s.so.1
7fadcc4ef000-7fadcc4f0000 rw-p 00000000 00:00 0
7fadcc50e000-7fadcc50f000 rw-p 00000000 00:00 0
7fadcc50f000-7fadcc624000 r-xp 00000000 00:1f 48050563 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libgfortran.so.3.0.0
7fadcc624000-7fadcc824000 ---p 00115000 00:1f 48050563 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libgfortran.so.3.0.0
7fadcc824000-7fadcc826000 rw-p 00115000 00:1f 48050563 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libgfortran.so.3.0.0
7fadcc826000-7fadcc911000 r-xp 00000000 00:1f 358755 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libstdc++.so.6.0.18
7fadcc911000-7fadccb10000 ---p 000eb000 00:1f 358755 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libstdc++.so.6.0.18
7fadccb10000-7fadccb18000 r--p 000ea000 00:1f 358755 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libstdc++.so.6.0.18
7fadccb18000-7fadccb1a000 rw-p 000f2000 00:1f 358755 /cvmfs/atlas.cern.ch/repo/ATLASLocalRootBase/x86_64/Gcc/gcc481_x86_64_slc6/slc6/x86_64-slc6-gcc48-opt/lib64/libstdc++.so.6.0.18
7fadccb1a000-7fadccb31000 rw-p 00000000 00:00 0
7fff71ab7000-7fff71b05000 rw-p 00000000 00:00 0 [stack]
7fff71bff000-7fff71c00000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
/project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob23: line 24: 6197 Aborted (core dumped) ../madevent_mintMC > log.txt < input_app.txt 2>&1
WARNING: program /project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob23 2 F 0 launch ends with non zero status: 134. Stop all computation
WARNING: Last 15 lines of logfile /project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/*/log.txt:
   Unknown return code (100): 0
   Unknown return code (10): 0
   Unit return code distribution (1):
 #Unit 1 = 2873
 #Unit 9 = 1
 Time spent in clustering : 0.00000000
 Time spent in PDF_Engine : 2.13991261
 Time spent in Reals_evaluation: 139.497101
 Time spent in IS_evaluation : 174.560303
 Time spent in OneLoop_Engine : 905.131775
 Time spent in PS_Generation : 0.968296051
 Time spent in other_tasks : 28.4944763
 Time spent in Total : 1250.79187
Time in seconds: 1251

INFO: remove job currently running
/project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob18: line 24: 3914 Terminated ../madevent_mintMC > log.txt < input_app.txt 2>&1
INFO: remove job currently running
/project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob19: line 24: 14431 Terminated ../madevent_mintMC > log.txt < input_app.txt 2>&1
/project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob22: line 24: 2518 Terminated ../madevent_mintMC > log.txt < input_app.txt 2>&1
/project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob24: line 24: 6395 Terminated ../madevent_mintMC > log.txt < input_app.txt 2>&1
/project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob25: line 24: 7462 Terminated ../madevent_mintMC > log.txt < input_app.txt 2>&1
INFO: remove job currently running
Command "launch auto " interrupted with error:
Exception : program /project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob23 2 F 0 launch ends with non zero status: 134. Stop all computation
Please report this bug on https://bugs.launchpad.net/madgraph5
More information is found in '/project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/run_01_tag_1_debug.log'.
Please attach this file to your report.
INFO:

quit
INFO:

quit

The log file is:
#************************************************************
#* MadGraph5_aMC@NLO *
#* *
#* * * *
#* * * * * *
#* * * * * 5 * * * * *
#* * * * * *
#* * * *
#* *
#* *
#* VERSION 2.2.2 2014-11-06 *
#* *
#* The MadGraph5_aMC@NLO Development Team - Find us at *
#* https://server06.fynu.ucl.ac.be/projects/madgraph *
#* and *
#* http://amcatnlo.cern.ch *
#* *
#************************************************************
#* *
#* Command File for aMCatNLO *
#* *
#* run as ./bin/aMCatNLO.py filename *
#* *
#************************************************************
launch auto
Traceback (most recent call last):
  File "/project/atlas/Users/twolf/MG5_aMC_v2_2_2/madgraph/interface/extended_cmd.py", line 879, in onecmd
    return self.onecmd_orig(line, **opt)
  File "/project/atlas/Users/twolf/MG5_aMC_v2_2_2/madgraph/interface/extended_cmd.py", line 872, in onecmd_orig
    return func(arg, **opt)
  File "/project/atlas/Users/twolf/MG5_aMC_v2_2_2/madgraph/interface/amcatnlo_run_interface.py", line 1190, in do_launch
    evt_file = self.run(mode, options)
  File "/project/atlas/Users/twolf/MG5_aMC_v2_2_2/madgraph/interface/amcatnlo_run_interface.py", line 1544, in run
    self.run_all(job_dict, [['2', 'F', '%d' % i]], status, split_jobs = split)
  File "/project/atlas/Users/twolf/MG5_aMC_v2_2_2/madgraph/interface/amcatnlo_run_interface.py", line 3161, in run_all
    self.wait_for_complete(run_type)
  File "/project/atlas/Users/twolf/MG5_aMC_v2_2_2/madgraph/interface/amcatnlo_run_interface.py", line 3125, in wait_for_complete
    self.cluster.wait(self.me_dir, update_status)
  File "/project/atlas/Users/twolf/MG5_aMC_v2_2_2/madgraph/various/cluster.py", line 587, in wait
    raise Exception, msg
Exception: program /project/atlas/Users/twolf/MG5_aMC_v2_2_2/bin/ttbb_gridpack_production/SubProcesses/P0_gg_tbbxtx/ajob23 2 F 0 launch ends with non zero status: 134. Stop all computation
Value of current Options:
              web_browser : None
              text_editor : None
        cluster_temp_path : None
       group_subprocesses : False
             syscalc_path : None
            cluster_queue : None
         madanalysis_path : /project/atlas/Users/twolf/MG5_aMC_v2_2_2/MadAnalysis
                   lhapdf : lhapdf-config
ignore_six_quark_processes : False
                    pjfry : None
    loop_optimized_output : True
    cluster_status_update : (600, 30)
   automatic_html_opening : False
                    gauge : unitary
               hepmc_path : None
             pythia8_path : /project/atlas/Users/twolf/pythia8205
                hwpp_path : None
                  amcfast : amcfast-config
       cluster_retry_wait : 300
      output_dependencies : external
          pythia-pgs_path : /project/atlas/Users/twolf/MG5_aMC_v2_2_2/pythia-pgs
                 mg5_path : /project/atlas/Users/twolf/MG5_aMC_v2_2_2
                  td_path : /project/atlas/Users/twolf/MG5_aMC_v2_2_2/td
             delphes_path : None
              thepeg_path : None
             cluster_type : condor
      exrootanalysis_path : /project/atlas/Users/twolf/MG5_aMC_v2_2_2/ExRootAnalysis
         fortran_compiler : None
                  nb_core : 6
                      OLP : MadLoop
              auto_update : 7
         cluster_nb_retry : 1
                 applgrid : applgrid-config
               eps_viewer : None
                  timeout : 60
                  fastjet : None
                    golem : None
      complex_mass_scheme : False
             cpp_compiler : None
             stdout_level : 20
                 run_mode : 2
#************************************************************
#* MadGraph5_aMC@NLO *
#* *
#* * * *
#* * * * * *
#* * * * * 5 * * * * *
#* * * * * *
#* * * *
#* *
#* *
#* VERSION 2.2.2 2014-11-06 *
#* *
#* The MadGraph5_aMC@NLO Development Team - Find us at *
#* https://server06.fynu.ucl.ac.be/projects/madgraph *
#* *
#************************************************************
#* *
#* Command File for MadGraph5_aMC@NLO *
#* *
#* run as ./bin/mg5_aMC filename *
#* *
#************************************************************
set group_subprocesses Auto
set ignore_six_quark_processes False
set loop_optimized_output True
set complex_mass_scheme False
define p = g u c d s u~ c~ d~ s~
define j = g u c d s u~ c~ d~ s~
define l+ = e+ mu+
define l- = e- mu-
define vl = ve vm vt
define vl~ = ve~ vm~ vt~
import model loop_sm
generate p p > t t~ b b~ [QCD]
output ttbb_gridpack_production
######################################################################
## PARAM_CARD AUTOMATICALY GENERATED BY MG5 FOLLOWING UFO MODEL ####
######################################################################
## ##
## Width set on Auto will be computed following the information ##
## present in the decay.py files of the model. ##
## See arXiv:1402.1178 for more details. ##
## ##
######################################################################

###################################
## INFORMATION FOR LOOP
###################################
Block loop
    1 9.118800e+01 # MU_R

###################################
## INFORMATION FOR MASS
###################################
Block mass
    5 4.700000e+00 # MB
    6 1.730000e+02 # MT
   15 1.777000e+00 # MTA
   23 9.118800e+01 # MZ
   25 1.250000e+02 # MH
## Dependent parameters, given by model restrictions.
## Those values should be edited following the
## analytical expression. MG5 ignores those values
## but they are important for interfacing the output of MG5
## to external program such as Pythia.
  1 0.000000 # d : 0.0
  2 0.000000 # u : 0.0
  3 0.000000 # s : 0.0
  4 0.000000 # c : 0.0
  11 0.000000 # e- : 0.0
  12 0.000000 # ve : 0.0
  13 0.000000 # mu- : 0.0
  14 0.000000 # vm : 0.0
  16 0.000000 # vt : 0.0
  21 0.000000 # g : 0.0
  22 0.000000 # a : 0.0
  24 80.419002 # w+ : cmath.sqrt(MZ__exp__2/2. + cmath.sqrt(MZ__exp__4/4. - (aEW*cmath.pi*MZ__exp__2)/(Gf*sqrt__2)))

###################################
## INFORMATION FOR SMINPUTS
###################################
Block sminputs
    1 1.325070e+02 # aEWM1
    2 1.166390e-05 # Gf
    3 1.180000e-01 # aS

###################################
## INFORMATION FOR YUKAWA
###################################
Block yukawa
    5 4.700000e+00 # ymb
    6 1.730000e+02 # ymt
   15 1.777000e+00 # ymtau

###################################
## INFORMATION FOR DECAY
###################################
DECAY 6 1.491500e+00 # WT
DECAY 23 2.441404e+00 # WZ
DECAY 24 2.047600e+00 # WW
DECAY 25 6.382339e-03 # WH
## Dependent parameters, given by model restrictions.
## Those values should be edited following the
## analytical expression. MG5 ignores those values
## but they are important for interfacing the output of MG5
## to external program such as Pythia.
DECAY 1 0.000000 # d : 0.0
DECAY 2 0.000000 # u : 0.0
DECAY 3 0.000000 # s : 0.0
DECAY 4 0.000000 # c : 0.0
DECAY 5 0.000000 # b : 0.0
DECAY 11 0.000000 # e- : 0.0
DECAY 12 0.000000 # ve : 0.0
DECAY 13 0.000000 # mu- : 0.0
DECAY 14 0.000000 # vm : 0.0
DECAY 15 0.000000 # ta- : 0.0
DECAY 16 0.000000 # vt : 0.0
DECAY 21 0.000000 # g : 0.0
DECAY 22 0.000000 # a : 0.0
#***********************************************************************
# MadGraph5_aMC@NLO *
# *
# run_card.dat aMC@NLO *
# *
# This file is used to set the parameters of the run. *
# *
# Some notation/conventions: *
# *
# Lines starting with a hash (#) are info or comments *
# *
# mind the format: value = variable ! comment *
#***********************************************************************
#
#*******************
# Running parameters
#*******************
#
#***********************************************************************
# Tag name for the run (one word) *
#***********************************************************************
  tag_1 = run_tag ! name of the run
#***********************************************************************
# Number of LHE events (and their normalization) and the required *
# (relative) accuracy on the Xsec. *
# These values are ignored for fixed order runs *
#***********************************************************************
  0 = nevents ! Number of unweighted events requested
  0.001 = req_acc ! Required accuracy (-1=auto determined from nevents)
  -1 = nevt_job ! Max number of events per job in event generation.
                 ! (-1= no split).
#***********************************************************************
# Normalize the weights of LHE events such that they sum or average to *
# the total cross section *
#***********************************************************************
  average = event_norm ! average or sum
#***********************************************************************
# Number of points per itegration channel (ignored for aMC@NLO runs) *
#***********************************************************************
  0.01 = req_acc_FO ! Required accuracy (-1=ignored, and use the
                     ! number of points and iter. below)
# These numbers are ignored except if req_acc_FO is equal to -1
  5000 = npoints_FO_grid ! number of points to setup grids
  4 = niters_FO_grid ! number of iter. to setup grids
  10000 = npoints_FO ! number of points to compute Xsec
  6 = niters_FO ! number of iter. to compute Xsec
#***********************************************************************
# Random number seed *
#***********************************************************************
  0 = iseed ! rnd seed (0=assigned automatically=default))
#***********************************************************************
# Collider type and energy *
#***********************************************************************
  1 = lpp1 ! beam 1 type (0 = no PDF)
  1 = lpp2 ! beam 2 type (0 = no PDF)
  6500 = ebeam1 ! beam 1 energy in GeV
  6500 = ebeam2 ! beam 2 energy in GeV
#***********************************************************************
# PDF choice: this automatically fixes also alpha_s(MZ) and its evol. *
#***********************************************************************
  nn23nlo = pdlabel ! PDF set
  244600 = lhaid ! if pdlabel=lhapdf, this is the lhapdf number
#***********************************************************************
# Include the NLO Monte Carlo subtr. terms for the following parton *
# shower (HERWIG6 | HERWIGPP | PYTHIA6Q | PYTHIA6PT | PYTHIA8) *
# WARNING: PYTHIA6PT works only for processes without FSR!!!! *
#***********************************************************************
  pythia8 = parton_shower
 #***********************************************************************
# Renormalization and factorization scales *
# (Default functional form for the non-fixed scales is the sum of *
# the transverse masses of all final state particles and partons. This *
# can be changed in SubProcesses/set_scales.f) *
#***********************************************************************
  F = fixed_ren_scale ! if .true. use fixed ren scale
  F = fixed_fac_scale ! if .true. use fixed fac scale
  91.188 = muR_ref_fixed ! fixed ren reference scale
  91.188 = muF1_ref_fixed ! fixed fact reference scale for pdf1
  91.188 = muF2_ref_fixed ! fixed fact reference scale for pdf2
#***********************************************************************
# Renormalization and factorization scales (advanced and NLO options) *
#***********************************************************************
  F = fixed_QES_scale ! if .true. use fixed Ellis-Sexton scale
  91.188 = QES_ref_fixed ! fixed Ellis-Sexton reference scale
  1 = muR_over_ref ! ratio of current muR over reference muR
  1 = muF1_over_ref ! ratio of current muF1 over reference muF1
  1 = muF2_over_ref ! ratio of current muF2 over reference muF2
  1 = QES_over_ref ! ratio of current QES over reference QES
#***********************************************************************
# Reweight flags to get scale dependence and PDF uncertainty *
# For scale dependence: factor rw_scale_up/down around central scale *
# For PDF uncertainty: use LHAPDF with supported set *
#***********************************************************************
  .true. = reweight_scale ! reweight to get scale dependence
  0.5 = rw_Rscale_down ! lower bound for ren scale variations
  2.0 = rw_Rscale_up ! upper bound for ren scale variations
  0.5 = rw_Fscale_down ! lower bound for fact scale variations
  2.0 = rw_Fscale_up ! upper bound for fact scale variations
  .false. = reweight_PDF ! reweight to get PDF uncertainty
  244601 = PDF_set_min ! First of the error PDF sets
  244700 = PDF_set_max ! Last of the error PDF sets
#***********************************************************************
# Merging - WARNING! Applies merging only at the hard-event level. *
# After showering an MLM-type merging should be applied as well. *
# See http://amcatnlo.cern.ch/FxFx_merging.htm for more details. *
#***********************************************************************
  0 = ickkw ! 0 no merging, 3 FxFx merging, 4 UNLOPS
#***********************************************************************
#
#***********************************************************************
# BW cutoff (M+/-bwcutoff*Gamma) *
#***********************************************************************
  15 = bwcutoff
 #***********************************************************************
# Cuts on the jets *
# Jet clustering is performed by FastJet.
# When matching to a parton shower, these generation cuts should be *
# considerably softer than the analysis cuts. *
# (more specific cuts can be specified in SubProcesses/cuts.f) *
#***********************************************************************
  1 = jetalgo ! FastJet jet algorithm (1=kT, 0=C/A, -1=anti-kT)
  0.7 = jetradius ! The radius parameter for the jet algorithm
  10 = ptj ! Min jet transverse momentum
  -1 = etaj ! Max jet abs(pseudo-rap) (a value .lt.0 means no cut)
#***********************************************************************
# Cuts on the charged leptons (e+, e-, mu+, mu-, tau+ and tau-) *
# (more specific gen cuts can be specified in SubProcesses/cuts.f) *
#***********************************************************************
  0 = ptl ! Min lepton transverse momentum
  -1 = etal ! Max lepton abs(pseudo-rap) (a value .lt.0 means no cut)
  0 = drll ! Min distance between opposite sign lepton pairs
  0 = drll_sf ! Min distance between opp. sign same-flavor lepton pairs
  0 = mll ! Min inv. mass of all opposite sign lepton pairs
  30 = mll_sf ! Min inv. mass of all opp. sign same-flavor lepton pairs
#***********************************************************************
# Photon-isolation cuts, according to hep-ph/9801442 *
# When ptgmin=0, all the other parameters are ignored *
#***********************************************************************
  20 = ptgmin ! Min photon transverse momentum
  -1 = etagamma ! Max photon abs(pseudo-rap)
  0.4 = R0gamma ! Radius of isolation code
  1.0 = xn ! n parameter of eq.(3.4) in hep-ph/9801442
  1.0 = epsgamma ! epsilon_gamma parameter of eq.(3.4) in hep-ph/9801442
  .true. = isoEM ! isolate photons from EM energy (photons and leptons)
#***********************************************************************
# Maximal PDG code for quark to be considered a jet when applying cuts.*
# At least all massless quarks of the model should be included here. *
#***********************************************************************
  4 = maxjetflavor
 #***********************************************************************
# For aMCfast+APPLGRID use in PDF fitting (http://amcfast.hepforge.org)*
#***********************************************************************
  0 = iappl ! aMCfast switch (0=OFF, 1=prepare APPLgrids, 2=fill grids)
#***********************************************************************
  244600 = lhaid

Thank you again!
Cheers,
Tim

Dear Rikkert,
I succeeded in producing a NLO-gridpack for pp>tt~bb~ [QCD] with the standard setup of mg5_aMC@NLO 2.1.2 with Pythia8. Should I just take this output in order to produce events or what do you suggest?
Cheers,
Tim

Thanks Rikkert Frederix, that solved my question.