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Re^3: ROUNDOFF ERROR IN BEND message when reading a Z matrix

Alex Granovsky


Firefly 7.1.G does not have this limitation on ifrzat array.

The quick description of DLC-related options can be found there:

Typically, one can easily resolve the "ERROR: UNABLE TO PROJECT DLC!"
error by adjusting corresponding threshold.

Hope this helps.

Alex Granovsky

On Mon Aug 2 '10 0:38am, Reinaldo Pis Diez wrote
>Thanks to Alex and Jim for their help/hints. I must say that I finally rearranged the original z matrix and freeze the internal coords using ifreez within $statpt.

>I'd like to mention that I couldn't use ifrzat together with dlc=.t. and auto=.t. because it is limited to 16 atoms in the current version and I have much more atoms to freeze.

>Also, I was unable to combine dlc=.t. and auto=.t. with ifzmat as Jim suggested. According to the INPUT section of the manual, ifzmat must have the same format as izmat. Thus, I try something like

> $zmat dlc=.t. auto=.t. ifzmat(1)=1,1,2, 1,1,3 $end

>to see what happens and got the message


>after the z matrix was automatically generated. I don't know what happens here, but it is clear that the problem is with ifzmat as if it is removed, the example runs smoothly. I guess that I'm missing something here. Can anyone provide a running example using dlc/auto/ifzmat?

>Thanks in advance.



>On Sat Jul 31 '10 2:02am, Jim Kress wrote
>>Why don't you just use

>>$ZMAT DLC=.true. AUTO=.true.  $END

>>to automatically generate your internal coordinates.  It's much more efficient and effective.  Then, if you want to freeze any of these internal coordinates, you can use the IFZMAT/FVALUE keywords in $ZMAT.

>>See page 32 (and following) in this documentation:


>>for more info.


>>On Mon Jul 26 '10 0:24am, Reinaldo Pis Diez wrote
>>>Dear folks,

>>>I'm using Firefly 7.1.G, build number 5618, to study a system containing about a hundred atoms. I'm using cartesian coordinates due to construction issues. Scf is ok, slow but convergent. Now, I have to optimize the neighborhood of a given atom, so I decide to use nzvar=3M-6 in $contrl, and "build" the z matrix in $zmat using zmat(1)=1,1,2, etc, etc. I've checked the z matrix and is ok with respect to connectivity issues.
>>>Despite the ifreez option I'm using to freeze almost all the internal coordinates, Firefly returns an error message during the reading of the z matrix in check mode:

>>>   --- ENCODED Z MATRIX ---
>>> COORD    TYPE     I    J    K    L    M    N
>>>     1       1     2    1
>>>     2       1     3    1
>>>   309       3   105   69   33   21

>>>where the 309th coord is the last one. What is the source of that error? (Almost) linear bond or torsion angles perhaps?
>>>I could provide the entire input if needed.
>>>Thanks in advance.


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