[molpro-user] visualizing imaginary modes with molden

[Dr Seth OLSEN]

Dear Molpro Users,

Is it possible to perform a forward-differenced-gradient frequency calculation in Z-matrix coordinates using molpro?  I have tried to add a 'coord,zmat' card to the frequency deck and it seems that it does not work.  The differentiation is still done in cartesians.  This is confusing to me because I believe that it is possible to generate a z-matrix coordinate based hessian in the context of a steepest-descent reaction path following calculation.  However, I would like to calculate the hessian first in a frequency calculation, and I would like to avoid the extra time needed to calculate the full 3N degrees of freedom for the molecule.  Can I do this?

Furthermore, it seems that when I output molden files for visualization of normal modes, the modes with imaginary frequency are not output in the molden file.  I am calculating the hessian on the excited state at the frank-condon point of a molecule, so there will be one or more imaginary frequency which I would like to visualize.  Can I get molpro to output these?

Cheers,

Seth Olsen



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Dr Seth Olsen, PhD
Postdoctoral Fellow, Computational Systems Biology Group
Centre for Computational Molecular Science
Chemistry Building,
The University of Queensland
Qld 4072, Brisbane, Australia

tel (617) 33653732
fax (617) 33654623
email: s.olsen1 at uq.edu.au
Web: www.ccms.uq.edu.au 

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