Hi, Paul<br>I think this two choice wonot make difference for FCC crystal. <br>And I do agree with your last statement .<br>Thanks Paolo and Axel, and Happy new year !<br><br>best wishes,<br>hai-ping<br><br><div class="gmail_quote">
On Tue, Dec 30, 2008 at 12:56 PM, Paul M. Grant <span dir="ltr"><<a href="mailto:w2agz@pacbell.net">w2agz@pacbell.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
OK, let's get specific...suppose I want to generate a uniformly distributed<br>
set of k-points for the reciprocal lattice of the primitive cell of an fcc<br>
lattice. The output of an scf run (and common sense matrix algebra) tells<br>
me the reciprocal lattice is defined as<br>
<br>
reciprocal axes: (cart. coord. in units 2 pi/a_0)<br>
b(1) = ( 1.000000 0.000000 0.000000 )<br>
b(2) = ( 0.000000 1.000000 0.000000 )<br>
b(3) = ( 0.000000 0.000000 1.000000 )<br>
<br>
OK (again)...I now generate a(n) uniformly distributed grid over the "b"<br>
vectors, and plot the points via xcrysden with PRIMVEC as above and see that<br>
grid fills the entire basic reciprocal cell (that is, with translation<br>
vector = O). No specification of celldm(1).<br>
<br>
Now, I want to input this grid to an nscf run via K_POINTS...is my grid<br>
"tpiba" or "crystal?"<br>
<br>
BTW, we (this community) owe a huge debt to Paolo and Axel.<br>
<div class="Ih2E3d"><br>
Paul M. Grant, PhD<br>
Principal, W2AGZ Technologies<br>
Visiting Scholar, Applied Physics, Stanford (2005-2008)<br>
EPRI Science Fellow (Retired)<br>
IBM Research Staff Member Emeritus<br>
<a href="mailto:w2agz@pacbell.net">w2agz@pacbell.net</a><br>
<a href="http://www.w2agz.com" target="_blank">http://www.w2agz.com</a><br>
<br>
<br>
<br>
</div><div><div></div><div class="Wj3C7c">-----Original Message-----<br>
From: <a href="mailto:pw_forum-bounces@pwscf.org">pw_forum-bounces@pwscf.org</a> [mailto:<a href="mailto:pw_forum-bounces@pwscf.org">pw_forum-bounces@pwscf.org</a>] On<br>
Behalf Of <a href="mailto:giannozz@democritos.it">giannozz@democritos.it</a><br>
Sent: Monday, December 29, 2008 12:29 PM<br>
To: <a href="mailto:pw_forum@pwscf.org">pw_forum@pwscf.org</a><br>
Subject: Re: [Pw_forum] K_POINTS, tpiba or crystal<br>
<br>
Quoting "Paul M. Grant" <<a href="mailto:w2agz@pacbell.net">w2agz@pacbell.net</a>>:<br>
<br>
> Frankly, I don't understand what "crystal" means wrt to reciprocal space<br>
<br>
it means "in units of the reciprocal lattice primitive vectors"<br>
<br>
Paolo<br>
<br>
<br>
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</div></div></blockquote></div><br><br clear="all"><br>-- <br>Hai-Ping Lan <br>Department of Electronics ,<br>Peking University , Bejing, 100871<br><a href="mailto:lanhaiping@gmail.com">lanhaiping@gmail.com</a>, <a href="mailto:hplan@pku.edu.cn">hplan@pku.edu.cn</a><br>