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Alex Granovsky

gran@classic.chem.msu.su

Dear Siddheshwar,

I'm sorry for misinterpreting your question.

The polarizability computed using TDHF/TDDFT is the electronic

polarizability. The only reason why it is not possible to enter

very small frequency values is that computed frequency-dependent

polarizability will in fact be virtually identical to the static one.

I can remove this check but this will be of little help to you.

Kind regards,

Alex

On Sat Jun 22 '13 10:27am, Siddheshwar Chopra wrote

---------------------------------------------------

>Dear Alex,

>Thats not exactly the answer for what I asked. I want to know what should be the values of FREQ(1) for frequencies corresponding to 1MHz to 20GHz. As I understood from the FIREFLY manual, I can only set a minimum of 0.000001 a.u. which corresponds to around 10e11 Hz. Thats the concern to me.. This range means that I can set a minimum of 100Ghz or so.. Please help.

>Regards,

>

>

>

>

>n Sat Jun 22 '13 6:09am, Alex Granovsky wrote

>----------------------------------------------

>>Dear Siddheshwar,

>>you can specify up to 10 frequencies at once.

>>Set nfreq to 10 and provide desired values

>>in the freq array. It is recommended to set the

>>first frequency to zero and enlist frequencies

>>in ascending order. Note they are given in atomic

>>units so you need to convert your MHz or GHz values

>>to atomic units.

>>Hope this helps.

>>Kind regards,

>>Alex

>>On Wed Jun 19 '13 2:24pm, Siddheshwar Chopra wrote

>>--------------------------------------------------

>>>Dear Alex,

>>>Thank you for the information. As per your input file, I ran the program to find polarizability of a molecule. I wish to ask that is it possible to give the FREQ(n) array for a range of 1MHz to 20GHz? Is it possible to get this frequency range in FIREFLY?

>>>Regards,

>>>On Tue Jun 18 '13 8:02pm, Alex Granovsky wrote

>>>----------------------------------------------

>>>>Dear Siddheshwar,

>>>>dielectric constant is a macroscopic property.

>>>>At microscopic level, we can compute frequency-dependent

>>>>polarizabilities and hyper-polarizabilities. Having a certain

>>>>model of the macroscopic body one can relate a microscopic

>>>>properties such as polarizability to a dielectric constant.

>>>>Below please find a sample file with computation of

>>>>frequency-dependent polarizability for benzene molecule

>>>>using PBE0 density functional. In brief, this is done

>>>>using runtyp=TDHF and specifying some DFTTYP.

>>>>If no DFTTYP is given, then these are indeed classical

>>>>TDHF calculations, if DFTTYP is given then they in fact

>>>>become TDDFT computations.

>>>>

$CONTRL SCFTYP=RHF DFTTYP=PBE0 runtyp=TDHF nosym=1 $END $SYSTEM TIMLIM=300 MEMORY=3000000 $END $BASIS GBASIS=N31 NGAUSS=6 NDFUNC=1 NPFUNC=1 $END $TDHF NFREQ=2 FREQ(1)=0,0.1 $END $DATA C6H6 Dnh 6 CARBON 6.0 -0.698164472 1.209256337 0.000000000 HYDROGEN 1.0 -1.241338149 2.150060743 0.000000000 $END

>>>>

>>>>

>>>>Kind regards,

>>>>Alex Granovsky

>>>>

>>>>

>>>>

>>>>

>>>>

>>>>

>>>>

>>>>On Fri Jun 14 '13 11:00am, Siddheshwar Chopra wrote

>>>>---------------------------------------------------

>>>>>Dear Sir,

>>>>>I would be glad if you could throw some light on How to calculate the frequency dependent Dielectric constant using FIREFLY?? As far as I have read, DFPT is used to do the same... please help.

>>>>>Regards,

Sun Jun 23 '13 2:07am

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