Sometimes, one has the bond topology but not the matching angle or dihedral definitions. Here is how to get them in VMD with topotools.
vmd > topo numbonds 352 vmd > topo numangles 332 vmd > topo clearangles vmd > topo numangles 0 vmd > topo guessangles vmd > topo numangles 414 vmd > animate write psf guessed.psf top psfplugin) Writing angles/dihedrals/impropers... Info) Opened coordinate file guessed.psf for writing. Info) Finished with coordinate file guessed.psf. 1