/usr/share/gromacs/top/amber96.ff/ is in gromacs-data 4.6.5-1build1.
This file is owned by root:root, with mode 0o755.
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/usr/share/gromacs/top/amber96.ff/aminoacids.arn
/usr/share/gromacs/top/amber96.ff/aminoacids.c.tdb
/usr/share/gromacs/top/amber96.ff/aminoacids.hdb
/usr/share/gromacs/top/amber96.ff/aminoacids.n.tdb
/usr/share/gromacs/top/amber96.ff/aminoacids.r2b
/usr/share/gromacs/top/amber96.ff/aminoacids.rtp
/usr/share/gromacs/top/amber96.ff/aminoacids.vsd
/usr/share/gromacs/top/amber96.ff/atomtypes.atp
/usr/share/gromacs/top/amber96.ff/dna.arn
/usr/share/gromacs/top/amber96.ff/dna.hdb
/usr/share/gromacs/top/amber96.ff/dna.r2b
/usr/share/gromacs/top/amber96.ff/dna.rtp
/usr/share/gromacs/top/amber96.ff/ffbonded.itp
/usr/share/gromacs/top/amber96.ff/ffnonbonded.itp
/usr/share/gromacs/top/amber96.ff/forcefield.doc
/usr/share/gromacs/top/amber96.ff/forcefield.itp
/usr/share/gromacs/top/amber96.ff/gbsa.itp
/usr/share/gromacs/top/amber96.ff/ions.itp
/usr/share/gromacs/top/amber96.ff/rna.arn
/usr/share/gromacs/top/amber96.ff/rna.hdb
/usr/share/gromacs/top/amber96.ff/rna.r2b
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/usr/share/gromacs/top/amber96.ff/spce.itp
/usr/share/gromacs/top/amber96.ff/tip3p.itp
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/usr/share/gromacs/top/amber96.ff/tip4pew.itp
/usr/share/gromacs/top/amber96.ff/tip5p.itp
/usr/share/gromacs/top/amber96.ff/urea.itp
/usr/share/gromacs/top/amber96.ff/watermodels.dat