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

Jim Kress

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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