## Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly

** Re^3: Can we calculate Frequency dependent dielectric constant of any sample? **
Alex Granovsky

gran@classic.chem.msu.su

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,

Sat Jun 22 '13 6:09am

This message read **873** times