/usr/share/gromacs/top/amber96.ff/rna.r2b is in gromacs-data 2018.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | ; rtp residue to rtp building block table
;GMX Force-field
A RA RA5 RA3 RAN
U RU RU5 RU3 RUN
C RC RC5 RC3 RCN
G RG RG5 RG3 RGN
|