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[Julie Smart <smart.julie@rocketmail.com>]

Hello Dr. Xifan Wu and the abinit users,

Let me ask my question the other way round to make it more clear.

In lesson: "trf1-5.in" the result of the dielectric tensor is:

"It is diagonal and isotropic, and corresponds to a dielectric constant of 9.7606048428 ."

In lesson "tnlo-2.in" as the result of the mrgddb we have:

Linear optical dielectric constant :
Electronic dielectric tensor = 9.20199931 (9.94846084)
 
Static dielectric constant :
Relaxed ion dielectric tensor = 10.95641891 (11.84823634)

To my understanding the result of "trf1-5.in" should be the same as the "Static dielectric constant" in "tnlo-2.in", please let me know if I am wrong.

Regards,
Julie

---

From: Xifan Wu <wuxifan@physics.rutgers.edu>
To: forum@abinit.org
Sent: Saturday, March 7, 2009 12:29:13 AM
Subject: Re: [abinit-forum] Calculating dielectric tensor

Hi Julie,

The clamped-ion tensor is the piezoelectric calculated only from the
electrons (wavefunctions), the relaxed-ion tensor including the ions'
response. The former can be measured in experiment with high-frequency
where the ions keep rigid, the latter is measured in experiment with
low frequency limit, where the ions can relax. Usually, the latter is
more often reported in the literatures.

Xifan


On Fri, 6 Mar 2009, Julie Smart wrote:

> Dear Abinit users,
>
> I have a question on calculating the dilectric tensor in ABINIT. In the response function calculation, in lesson "trf1-5.in", we have calculated the dielectric tensor for AlAs. Also, "Electronic dielectric tensor" and "Relaxed ion dielctric tensor" has been calculated in "tnlo-2".in and ... .
>
> I want to know what the difference between these dielectric tensors is. If the dielectric tensor calculated from response function to homogeneous electric field is the "Relaxed ion dielctric tensor", why do their values differ in "tnlo-2.in" and "trf1-5.in"?
>
> Regards,
> Julie
>
>
>
>