/usr/share/gromacs/top/amber03.ff/urea.itp is in gromacs-data 2018.1-1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 | [ moleculetype ]
; molname nrexcl
URE 3
[ atoms ]
1 C 1 URE C 1 0.880229 12.01000 ; amber C type
2 O 1 URE O 2 -0.613359 16.00000 ; amber O type
3 N 1 URE N1 3 -0.923545 14.01000 ; amber N type
4 H 1 URE H11 4 0.395055 1.00800 ; amber H type
5 H 1 URE H12 5 0.395055 1.00800 ; amber H type
6 N 1 URE N2 6 -0.923545 14.01000 ; amber N type
7 H 1 URE H21 7 0.395055 1.00800 ; amber H type
8 H 1 URE H22 8 0.395055 1.00800 ; amber H type
[ bonds ]
1 2
1 3
1 6
3 4
3 5
6 7
6 8
[ dihedrals ]
; ai aj ak al funct definition
2 1 3 4 9
2 1 3 5 9
2 1 6 7 9
2 1 6 8 9
3 1 6 7 9
3 1 6 8 9
6 1 3 4 9
6 1 3 5 9
[ dihedrals ]
3 6 1 2 4
1 4 3 5 4
1 7 6 8 4
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