<P> Dear all</P>
<P> I attach 8 carbonyl groups onto a carbon nanotube (CNT). Each carbonyl group is considered as a residue named "Car" and each carbon atom in the CNT is considered as a residue named "Gr1". In the mdp file, the freezegrps are Gr1 and Car, and the freezedim are Y Y Y Y Y Y. Does it mean that all the C in the CNT and C and O in the carbonyl groups are fixed in three dimensions and they can not move in any direction. However, when I made the energy minimization, the coordinates of C and O in carbonyl groups changed.</P>
<P> How can I really fix the atoms? Look forward for your suggestions!</P>
<P>Yours Sincerely</P>
<P>Toby</P>