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Re^4: Difference between excited state and ground state density

Michal Krompiec

Dear Alex,
Thanks, that's clear. So is it possible to generate a CUBE with relaxed TDDFT density itself? If I specify the state of interest in $tddft and $dft tdprp=.t. $end  $ELDENS IEDEN=1 $END  $CUBE CUBE=.T. $END, will the relaxed TDDFT density be punched?
Best regards,

On Wed Jun 15 '16 9:14pm, Alex Granovsky wrote
>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)

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