## Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly

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

gran@classic.chem.msu.su

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,

Tue Jun 18 '13 8:02pm

This message read **724** times