[Pw_forum] phonon at G error : from phq_readin : error # 1 no elec. field with metals

[xu yuehua]

Dear Prof Nicola Marzari:
thank you for your help  , i am really grateful  i will read the paper and
book  you have recommended to me.
if there is some question about the paper i would like to consult with you
.Hope get your help .

Xu Yuehua

07.05.22


2007/5/22, Nicola Marzari <marzari at mit.edu>:
>
> xu yuehua wrote:
> > yes,before pho calculation ,i have computed "scf" .the water. in is this
> >  &system
> > ibrav     = 0,
> >   nat       = 15,
> >   ntyp      = 2,
> >   ecutwfc   = 29.98744D0,
> >   ecutrho   =200
> >   occupations = "smearing",
> >   smearing    = "gauss",
> >   degauss     = 0.003D0,
> > if it is unsuitable ,i have no idea to use what occupations and so on
> > .please help me .thanks
>
>
>
> > my name is xu yuehua
> > affilation: physics depatment
> >  nanjing university china.
>
> Dear Xu,
>
> welcome to the gang.
>
> There are two comments to make here - if you want your calculation to
> work, start by droppping the keywords for occupations, smearing, and
> degauss. Those three are used for systems with fractional occupations -
> these are typically metals, and that's why phonon stopped. By the
> way, "Phonon" calculation for the water molecule and the water dimer
> are available in a 2005 JCP by Sit and Marzari - you could compare your
> results and parameters with those.
>
> The second comment is that even completing your calculations
> successfully won't be very helpful, if you do not first become
> experienced in this kind of calculations.
>
> Now, I'm not sure what to suggest - there is a book on "Electronic
> Structure" by Richard Martin that is outstanding, but a bit advanced.
> A more introductory one has recently come out, by Jorge Kohanoff
> ("Electronic Structure Calculations for Solids and Molecules).
>
> I might sound self-serving, but our graduate class on atomistic
> modeling of materials (including video lectures, and pwscf homework),
> is fully on the web, linked from
> http://quasiamore.mit.edu/pmwiki/index.php?n=Main.Teaching ).
> This class takes MIT students of different backgrounds, and that
> have never seen computational modeling, through a basic knowledge
> of the fundamentals.
>
>                                nicola
>
>
> --
> ---------------------------------------------------------------------
> 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
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>



-- 
Xu Yuehua
physics Department of Nanjing university
China
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