[gmx-users] error on graphene sheet simulation

[Devargya Chakraborty]

while going through your tutorial on graphene sheet i was facing an error.
https://erastova.xyz/teaching/practical-simulations-for-molecules-and-materials/material-simulations/graphene-simulation-set-up/

NOTE 2 [file nvt.mdp]:
  The Berendsen thermostat does not generate the correct kinetic energy
  distribution. You might want to consider using the V-rescale thermostat.

Setting the LD random seed to 164492569
Generated 20503 of the 20503 non-bonded parameter combinations
Generating 1-4 interactions: fudge = 1
Generated 17396 of the 20503 1-4 parameter combinations

ERROR 1 [file GRA.itp, line 7]:
  Atomtype CG2R61 not found


There were 2 notes

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Program:     gmx grompp, version 2019.1
Source file: src/gromacs/gmxpreprocess/toppush.cpp (line 1333)

Fatal error:
There was 1 error in input file(s)

For more information and tips for troubleshooting, please check the GROMACS
website at http://www.gromacs.org/Documentation/Errors
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can you give any suggestion what could have gone wrong...
thanks