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Re^2: Difference between excited state and ground state density

Michal Krompiec

Dear Alex,
Thanks. So if I generate the difference density in a TDDFT restart job (restarting from a converged TDDFT calculation, using $TDDFT RDTDVC=.t. $END ), this should be the difference between the input TDDFT density and the KS ground state density, right?
Best regards,

On Sun Jun 12 '16 10:33am, Alex Granovsky wrote
>Dear Michal,

>I'm sorry for delayed reply.

>The exact answer to your question depends on computational method.
>The general comment is that if you add the following option to your
>input file,


 $eldens diffd=.t. $end

>(This option is documented here:

> )

>then Firefly will automatically compute and punch the differences
>between two consecutive densities. This may require setting proper
>iroot or istate keyword depending on particular computational method.

>Unfortunately this does not work well for TDDFT as normally one is
>interested in difference of relaxed density and KS density while
>Firefly would computes two differences:
>one between non-relaxed TDDFT density and KS densities and second
>between relaxed and non-relaxed TDDFT densities. To make this work
>one needs to specify proper nstate and istate in $tddft group and
>adds tdprp=.t. to $dft group.

>As to second part of your question, I'd suggest you to use gOpenMol
>to manipulate cubes and plt files. First, gOpenMol distribution
>contains gamess2plt utility that was developed to extract $CUBE
>information from the PC GAMESS/Firefly punch files and convert them to
>plt files. Second, there is an utility called contman that can be used
>to add or subtract two plt files. Finally, plt files can be visualised
>by either gOpenMol or by (the better way) Chimera and probably by some
>other visualizer. In addition, powerful general purpose vilualizers
>like VisIt and ParaView accepts cube files and can manipulate them.
>All the best,
>On Wed Jun 8 '16 4:09pm, Michal Krompiec wrote
>>Hi, how can I generate a CUBE file for the difference in electron density between a chosen excited state and the ground state? If it is not possible directly, can I subtract the respective CUBEs with some external software? (other than ChemCraft)

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