Topology and parameter files

[Jodi Lubetsky]

I am working on a crystal structure of hydroxyphenylpyruvate complexed to a
protein.  I used xplo2d to generate my topology and parameter files for HPP,
yet i am having some difficulties.  HPP remains planar, even after rounds of
positional refinement.  Is there a way to change the topology and parameter
files such that the molecule is free to rotate about its single bonds?

Thanks in advance,
Jodi