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Re: Constrains for dihedrals in geometry optimization

Luca Maidich
luca.maidich@gmail.com

Good day Pavel,
in your freezed coordinate I think there's a mistake, if you look at the manual at the voice IZMAT you will see that a dihedral angle is defined as the torsion angle between planes I-J-K and J-K-L.
Your definition takes 2 atoms from one side and the other two from the other. In this may not work.

By the way you can use the DLC automatic definition if there's no obligation to use ZMT. You can use Cartesian geometry (or the same ZMT that you have in your file) and add the following line to your input file
$ZMAT DLC=.T. AUTO=.T. IFZMAT(1)=3,13,3,4,12 AUTOFV=.F. FVALUE=5.0 $END
the meaning of the keyword can be found in the manual. Remember to remove all other things in IZMAT.

Best Regards
Luca Maidich

[ This message was edited on Mon Sep 12 '11 at 8:03pm by the author ]

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