[Pw_forum] Question about induced dipole moment
lanhaiping at gmail.com
Wed Sep 19 12:51:21 CEST 2007
Thank you, Prof Marzari.
As far as i know, the changes of the WFs' centers can be applied to
While for metallic or semi-metallic systems, Is such scheme still useful ?
in fact, i still donot know how to define the wfs' centers for metallic
i found it is hard to achieve convergence when i applied electric-enthalpy
metallic systems no matter which direction of the uniform electric field
i do notice the difficulties of scf convergence of systems under electric
field. i tried to
reduce mixing parameter , or increase the smearing width, but no success.
any other parameters i should pay attention to ?
On 9/19/07, Nicola Marzari <marzari at mit.edu> wrote:
> Dear Hai-Ping,
> it was done directly with real space integration - i.e. in the
> transferse direction, the dipole is given by the integral of r rho(r).
> It could also be done by looking at the change in position of the
> sum of the centers of the Wannier functions - this is less accurate,
> since the reciprocal-space expression for the position operator is
> based on a finite-differences discretization.
> lan haiping wrote:
> > Hi, All.
> > I have read a work of Prof Marzari performed by QE package to
> > compute static dielectric properties of nanotube systems : PRL 96,
> > To extract dielectric quantities, there are 2 methods mentioned in
> > this work. I have a question about the method adopted by the sawtooth
> > potential . In order to obtain transverse polarizability , we need know
> > the dipole moment induced by external sawtooth potential . I have done
> > several tests on similar systems carbon nanotube (6,0), but i have not
> > found how to extract such induced dipole moment .
> > Would anyone please give me a hand on this subject ? Any tips or
> > references are appreciated !
> > Best wishes
> > Hai-Ping
> Prof Nicola Marzari Department of Materials Science and Engineering
> 13-5066 MIT 77 Massachusetts Avenue Cambridge MA 02139-4307 USA
> tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu
> Pw_forum mailing list
> Pw_forum at pwscf.org
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping at gmail.com, hplan at pku.edu.cn
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