Fatal eror adding entry in rtp

User discussions
1

Hello everyone,
Im trying to add NH3 terminal in the amber forcefield by modifying the rtp entry as below

 [ NH3 ]
 [ atoms ]
     N    N     -0.267522   ; charge from RESP
    H1    H      0.422507   ; charge from RESP
    H2    H      0.422507   ; charge from RESP
    H3    H      0.422507   ; charge from RESP
 [ bonds ]
     N    H1
     N    H2
     N    H3
    -C    N     ; bond to the previous C-terminus
 [ impropers ]
     N    H1    H2    H3

when i invoke pdb2gmx i get the following error

Reading residue database... (Amber99sb-ildn)
Opening force field file ./amber99sb-ildn.ff/aminoacids.rtp

-------------------------------------------------------
Program:     gmx pdb2gmx, version 2023.3
Source file: src/gromacs/gmxpreprocess/resall.cpp (line 465)

Fatal error:
in .rtp file in residue NH3 at line:
     N    N     -0.267522
2

I think it’s because the last column of atom numbers in [ atoms ] are missing.