[Pw_forum] K_POINTS, tpiba or crystal

[lan haiping]

Hi, Paul
I think this two choice wonot make difference for FCC crystal.
And I do agree with your last statement .
Thanks  Paolo and Axel, and Happy new year !

best wishes,
hai-ping

On Tue, Dec 30, 2008 at 12:56 PM, Paul M. Grant <w2agz at pacbell.net> wrote:

> OK, let's get specific...suppose I want to generate a uniformly distributed
> set of k-points for the reciprocal lattice of the primitive cell of an fcc
> lattice.  The output of an scf run (and common sense matrix algebra) tells
> me the reciprocal lattice is defined as
>
> reciprocal axes: (cart. coord. in units 2 pi/a_0)
>               b(1) = (  1.000000  0.000000  0.000000 )
>               b(2) = (  0.000000  1.000000  0.000000 )
>               b(3) = (  0.000000  0.000000  1.000000 )
>
> OK (again)...I now generate a(n) uniformly distributed grid over the "b"
> vectors, and plot the points via xcrysden with PRIMVEC as above and see
> that
> grid fills the entire basic reciprocal cell (that is, with translation
> vector = O).  No specification of celldm(1).
>
> Now, I want to input this grid to an nscf run via K_POINTS...is my grid
> "tpiba" or "crystal?"
>
> BTW, we (this community) owe a huge debt to Paolo and Axel.
>
> Paul M. Grant, PhD
> Principal, W2AGZ Technologies
> Visiting Scholar, Applied Physics, Stanford (2005-2008)
> EPRI Science Fellow (Retired)
> IBM Research Staff Member Emeritus
> w2agz at pacbell.net
> http://www.w2agz.com
>
>
>
> -----Original Message-----
> From: pw_forum-bounces at pwscf.org [mailto:pw_forum-bounces at pwscf.org] On
> Behalf Of giannozz at democritos.it
> Sent: Monday, December 29, 2008 12:29 PM
> To: pw_forum at pwscf.org
> Subject: Re: [Pw_forum] K_POINTS, tpiba or crystal
>
> Quoting "Paul M. Grant" <w2agz at pacbell.net>:
>
> > Frankly, I don't understand what "crystal" means wrt to reciprocal space
>
> it means "in units of the reciprocal lattice primitive vectors"
>
> Paolo
>
>
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-- 
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
lanhaiping at gmail.com, hplan at pku.edu.cn
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