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Re^3: Difference between excited state and ground state density

Alex Granovsky

Dear Michal,

unfortunately this still should produce the difference between KS
density and unrelaxed TDDFT density. To obtain relaxed TDDFT density,
it is necessary to perform additional computations besides TDDFT
energy calculations.

Kind regards,

On Mon Jun 13 '16 3:53pm, Michal Krompiec wrote
>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)

[ This message was edited on Wed Jun 15 '16 at 9:14pm by the author ]

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