## Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly

** Re^4: Calculation of dielectric constant at Freq= 1KHz.. Help needed. **
Siddheshwar Chopra

sidhusai@gmail.com

Dear Alex,

I completely agree with you on the static dielectric point. I got my answer. But could you also describe how this static dielectric constant is calculated from the TDHF calculation (attached earlier)? It would be a great help.Kind regards,

On Wed Jul 29 '15 1:07am, Alex Granovsky wrote

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

>Hello,

>I believe at 1 KHz dielectric constant will be almost exactly as

>dielectric constant at 0 Hz i.e. the static one.

>

>

>Firefly calculates only electronic part of polarizability and hyper-

>polarizabilities. To compute dielectric constant at such a low

>frequency as 1 KHz you need also to know nuclear contributions

>to polarizability. It is impossible to compute them using Firefly.

>Note, polarizability is a property of micro-objects while dielectric

>constant is a macro-property. You need to use some model to deduce

>macro property from the micro one.

>Kind regards,

>Alex Granovsky

>

>

>

>On Fri Jul 24 '15 11:03am, Siddheshwar Chopra wrote

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

>>Dear Alex,

>>Please find attached the new output file.. Please tell me about the calculation of dielectric constant.

>>Kind Regards,

>>On Tue Jul 21 '15 4:56pm, Alex Granovsky wrote

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

>>>Hello,

>>>your input structure is invalid. The terminal C atoms should be properly terminated.

>>>Regards,

>>>Alex Granovsky

>>>

>>>

>>>On Tue Jul 14 '15 8:41am, Siddheshwar Chopra wrote

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

>>>>Dear Users,

>>>>This is the very first time that I have tried finding the dielectric constant using FIREFLY.. I have attached an output file for your reference. I wanted to find the dielectric constant at Frequency=1 KHz. For the same, I have added "1.519835E-13" to the Freq(1) array. I would be really grateful if you all can help me understand HOW to calculate the dielectric constant from the o/p file.

>>>>Also, as you can see, I have used classical calculations here.

>>>>In addition, I request Alex Sir to tell the Frequency range (in KHz) in which we can find the dielectric constant..

>>>>

>>>>

>>>>Kind Regards,

Wed Jul 29 '15 2:31pm

This message read **352** times