Alex Granovsky
gran@classic.chem.msu.su
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
>>>>>Regards,