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Re^5: Calculation of dielectric constant at Freq= 1KHz.. Help needed.

Alex Granovsky

Dear Jim,

When field frequency is high, one can neglect nuclear response
(because nuclear motion is much slower than the oscillations of
electric field). In this situation one can use computed
polarizability together with the Clausius–Mossotti relation to
find dielectric constant.

Kind Regards,

On Wed Jul 29 '15 7:15pm, Jim Kress wrote
>The dielectric constant is a macroscopic property.  Unless one used QMD (or regular MD), I do not understand how Firefly can provide a dielectric constant.

>How does it do this?


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

>>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

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

>>>>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,

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