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[abinit-forum] Tutorial 3.1: nshiftk & shiftk meaningless?

From: Rob <spamrefuse@yahoo.com>
To: abinit <forum@abinit.org>
Subject: [abinit-forum] Tutorial 3.1: nshiftk & shiftk meaningless?
Date: Thu, 18 Jun 2009 00:39:24 -0700 (PDT)
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Hi,

Tutorial 3.1 introduces the variables nshiftk and shiftk.
This is quite confusing to me. I don't see what is shifted?

Moreover:
The total energy is EXACTLY the same as when I remove
these two variables from the input file t31.in:

With
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5
I get
etotal -8.8662238960E+00

When I change it into the default values:
nshiftk 1
shiftk 0.5 0.5 0.5
I get:
etotal -8.8662238960E+00 (EXACTLY the same energy).

I have tried the above for different ngkpt values (2 2 2, 4 4 4, 6 6 6)
with the same conclusion!

What is then the purpose of this tutorial 3.1?
This confuses me quite a bit, since I tried to understand nshiftk and shiftk.

Thanks,
Rob.

[abinit-forum] Tutorial 3.1: nshiftk & shiftk meaningless?, Rob, 06/18/2009
- Re: [abinit-forum] Tutorial 3.1: nshiftk & shiftk meaningless?, matthieu verstraete, 06/18/2009