How to generate topology for a single aminoacid residue?

GROMACS version:2016.3
GROMACS modification: Yes/No
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I have tried to simulate only one alanine residue with the available FFs of AMBER, GROMOS, CHARMM and OPLS. Later came to know that AMBER FFs do not support for standalone residues. So, which FF will be suitable for simulating individual aminoacid residue.