[Pw_forum] K_POINTS, tpiba or crystal
Paul M. Grant
w2agz at pacbell.net
Sun Jan 4 00:38:16 CET 2009
Followup on K_POINTS: tpiba vs crystal...
As usual, Paolo is right...for sc lattices (ibrav=1), tpiba or crystal give
equal nscf outputs.
But, for fcc lattices (ibrav=2), it apparently does! See below comparing
nscf k-vector outputs for tpiba and crystal, and crystal is very different
(and weird...for me anyway). BTW, whether tpiba, etc., should be enclosed
in curly braces or parentheses or nothing on the K_POINTS card is confusing.
PW_INPUT shows braces, but parenthese work too, and probably no delimiters
as well.
My agenda here is to generate k-points grids amenable to applications that
cannot use simply MP weighted points in the irreducible BZ, such as
epsilon.x. I'm finding the algorithm used by Eyvaz Isaev for Fermi Surface
plotting which uniformly populate and span the fundamental reciprocal
lattice cell works quite well...if inputted with tpiba or "blank," not
crystal.
TPIBA VS CRYSTAL COMPARISON RE FCC FOLLOWS
===================================================
TPIBA
nsfc run input (partial) (Al, ibrav=2)
K_POINTS {tpiba}
2197
0.00000000 0.00000000 0.00000000 1.00000000
-0.08333333 0.08333333 -0.08333333 1.00000000
-0.16666667 0.16666667 -0.16666667 1.00000000
-0.25000000 0.25000000 -0.25000000 1.00000000
-0.33333333 0.33333333 -0.33333333 1.00000000
-0.41666667 0.41666667 -0.41666667 1.00000000
-0.50000000 0.50000000 -0.50000000 1.00000000
-0.58333333 0.58333333 -0.58333333 1.00000000
-0.66666667 0.66666667 -0.66666667 1.00000000
-0.75000000 0.75000000 -0.75000000 1.00000000
-0.83333333 0.83333333 -0.83333333 1.00000000
-0.91666667 0.91666667 -0.91666667 1.00000000
-1.00000000 1.00000000 -1.00000000 1.00000000
0.08333333 0.08333333 0.08333333 1.00000000
0.00000000 0.16666667 0.00000000 1.00000000
-0.08333333 0.25000000 -0.08333333 1.00000000
-0.16666667 0.33333333 -0.16666667 1.00000000
-0.25000000 0.41666667 -0.25000000 1.00000000
-0.33333333 0.50000000 -0.33333333 1.00000000
....................
nsfc run output (partial) (Al, ibrav=2)
reciprocal axes: (cart. coord. in units 2 pi/a_0)
b(1) = ( -1.000000 -1.000000 1.000000 )
b(2) = ( 1.000000 1.000000 1.000000 )
b(3) = ( -1.000000 1.000000 -1.000000 )
number of k points= 2197 gaussian broad. (Ry)= 0.0150 ngauss = 0
cart. coord. in units 2pi/a_0
k( 1) = ( 0.0000000 0.0000000 0.0000000), wk = 0.0009103
k( 2) = ( -0.0833333 0.0833333 -0.0833333), wk = 0.0009103
k( 3) = ( -0.1666667 0.1666667 -0.1666667), wk = 0.0009103
k( 4) = ( -0.2500000 0.2500000 -0.2500000), wk = 0.0009103
k( 5) = ( -0.3333333 0.3333333 -0.3333333), wk = 0.0009103
k( 6) = ( -0.4166667 0.4166667 -0.4166667), wk = 0.0009103
k( 7) = ( -0.5000000 0.5000000 -0.5000000), wk = 0.0009103
k( 8) = ( -0.5833333 0.5833333 -0.5833333), wk = 0.0009103
k( 9) = ( -0.6666667 0.6666667 -0.6666667), wk = 0.0009103
k( 10) = ( -0.7500000 0.7500000 -0.7500000), wk = 0.0009103
k( 11) = ( -0.8333333 0.8333333 -0.8333333), wk = 0.0009103
k( 12) = ( -0.9166667 0.9166667 -0.9166667), wk = 0.0009103
k( 13) = ( -1.0000000 1.0000000 -1.0000000), wk = 0.0009103
k( 14) = ( 0.0833333 0.0833333 0.0833333), wk = 0.0009103
k( 15) = ( 0.0000000 0.1666667 0.0000000), wk = 0.0009103
k( 16) = ( -0.0833333 0.2500000 -0.0833333), wk = 0.0009103
============================================================================
CRYSTAL
nsfc run input (partial) (Al, ibrav=2)
K_POINTS {crystal}
2197
0.00000000 0.00000000 0.00000000 1.00000000
-0.08333333 0.08333333 -0.08333333 1.00000000
-0.16666667 0.16666667 -0.16666667 1.00000000
-0.25000000 0.25000000 -0.25000000 1.00000000
-0.33333333 0.33333333 -0.33333333 1.00000000
-0.41666667 0.41666667 -0.41666667 1.00000000
-0.50000000 0.50000000 -0.50000000 1.00000000
-0.58333333 0.58333333 -0.58333333 1.00000000
-0.66666667 0.66666667 -0.66666667 1.00000000
-0.75000000 0.75000000 -0.75000000 1.00000000
-0.83333333 0.83333333 -0.83333333 1.00000000
-0.91666667 0.91666667 -0.91666667 1.00000000
-1.00000000 1.00000000 -1.00000000 1.00000000
0.08333333 0.08333333 0.08333333 1.00000000
0.00000000 0.16666667 0.00000000 1.00000000
-0.08333333 0.25000000 -0.08333333 1.00000000
-0.16666667 0.33333333 -0.16666667 1.00000000
-0.25000000 0.41666667 -0.25000000 1.00000000
-0.33333333 0.50000000 -0.33333333 1.00000000
-0.41666667 0.58333333 -0.41666667 1.00000000
...................
nsfc run output (partial) (Al, ibrav=2)
reciprocal axes: (cart. coord. in units 2 pi/a_0)
b(1) = ( -1.000000 -1.000000 1.000000 )
b(2) = ( 1.000000 1.000000 1.000000 )
b(3) = ( -1.000000 1.000000 -1.000000 )
number of k points= 2197 gaussian broad. (Ry)= 0.0150 ngauss =
cart. coord. in units 2pi/a_0
k( 1) = ( 0.0000000 0.0000000 0.0000000), wk = 0.0009103
k( 2) = ( 0.2500000 0.0833333 0.0833333), wk = 0.0009103
k( 3) = ( 0.5000000 0.1666667 0.1666667), wk = 0.0009103
k( 4) = ( 0.7500000 0.2500000 0.2500000), wk = 0.0009103
k( 5) = ( 1.0000000 0.3333333 0.3333333), wk = 0.0009103
k( 6) = ( 1.2500000 0.4166667 0.4166667), wk = 0.0009103
k( 7) = ( 1.5000000 0.5000000 0.5000000), wk = 0.0009103
k( 8) = ( 1.7500000 0.5833333 0.5833333), wk = 0.0009103
k( 9) = ( 2.0000000 0.6666667 0.6666667), wk = 0.0009103
k( 10) = ( 2.2500000 0.7500000 0.7500000), wk = 0.0009103
k( 11) = ( 2.5000000 0.8333333 0.8333333), wk = 0.0009103
k( 12) = ( 2.7500000 0.9166667 0.9166667), wk = 0.0009103
k( 13) = ( 3.0000000 1.0000000 1.0000000), wk = 0.0009103
k( 14) = ( -0.0833333 0.0833333 0.0833333), wk = 0.0009103
k( 15) = ( 0.1666667 0.1666667 0.1666667), wk = 0.0009103
k( 16) = ( 0.4166667 0.2500000 0.2500000), wk = 0.0009103
k( 17) = ( 0.6666667 0.3333333 0.3333333), wk = 0.0009103
k( 18) = ( 0.9166667 0.4166667 0.4166667), wk = 0.0009103
k( 19) = ( 1.1666667 0.5000000 0.5000000), wk = 0.0009103
k( 20) = ( 1.4166667 0.5833333 0.5833333), wk = 0.0009103
k( 21) = ( 1.6666667 0.6666667 0.6666667), wk = 0.0009103
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 Paolo Giannozzi
Sent: Tuesday, December 30, 2008 5:21 AM
To: PWSCF Forum
Subject: Re: [Pw_forum] K_POINTS, tpiba or crystal
On Tuesday 30 December 2008 05:56, Paul M. Grant wrote:
> b(1) = ( 1.000000 0.000000 0.000000 )
> b(2) = ( 0.000000 1.000000 0.000000 )
> b(3) = ( 0.000000 0.000000 1.000000 )
these are the lattice vectors generating a simple cubic lattice
> Now, I want to input this grid to an nscf run via K_POINTS...is my grid
> "tpiba" or "crystal?"
in this particular case, it shouldn't matter, since the crystal and
cartesian axis are the same, and the length of crystal axis is 2pi/a .
Paolo
--
Paolo Giannozzi, Democritos and Udine University
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