The ABINIT Users Mailing List ( CLOSED )

[Nicola Marzari <marzari@mit.edu>]

One side comment - it can become more efficient if the unit cell 
contains many inequivalent atoms.

Suppose you have 100 atoms - usually, you would need to displace each of 
them, one by one, in the three crystallographic directions, and
calculate the resulting polarization (this can be done either with
linear-response theory, i.e. as the response to an infinitesimal 
displacement, or with the Berry phase, as the response to a finite one).

Instead, you can apply a small electric field three times (in 3 non 
equivalent directions), and you have right away the effective charges 
for all the 100 atoms. Similar considerations apply, say, if you wanted
to calculate Raman couplings.


                                nicola


Xinjie Wang wrote:
> Hi David,
>
> This feature (B.10) does not give more efficient/accurate calculations
> of the static dielectric properties. It allows the calculation of
> electric-field-dependence of Born effective charges and dielectric 
> tensor. You can read this paper, Phys. Rev. B 75, 115116 (2007),
> for details.
>
> Regards,
> Xinjie
>
> david.hendry@mandmd.com.au wrote:
> > Dear Abinitors,
> >
> > I'm interested in the static dielectric constant of 
> > ceramics/insulators.  I notice the latest release notes of Abinit: 
> > "B.10 Born effective charges and dielectric tensor calculations can 
> > now be computed in a finite electric field." 
> > Does this feature or any other new feature (from 5.3.4) allow a more 
> > efficient/accurate calculation of the static dielectric properties?
> >
> > Sincerely,
> >
> > David.


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Prof Nicola Marzari   Department of Materials Science and Engineering
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