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Re^5: ROUNDOFF ERROR IN BEND message when reading a Z matrix

Alex Granovsky


actually, as described in manual, you can construct DLCs manually
from any set of internals. You'll need to provide SIJ and IJS arrays.

E.g., this is the way how one could build Natural Internal Coordinates.

However, this is not the recommended way how to work with internals.

Alex Granovsky

>The strange thing here (to me at least) is that the manual states that ifzmat is used to freeze some internal coords but the dlc generates delocalized coords, which are usually much more that 3N-6. Then, how should I connect the two coord types?

>Let me make things clearer: for a trial system X(OH)4, there are 21 internal coords. However, dlc/auto generates 30 coords. After that, the program prints

>and the expected 21 internal coords are expressed as combination of the 30 delocalized ones. I could easily identify bonds and angles by looking at the table of automatically generated coords but the identification of the internal coords generated as above is not so easy at all. I understand that ifzmat acts on the internal coords then, how could I "see" what coords to freeze?      

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