[Pw_forum] improper symmetry analysis

Kun Yin kyin.cn at gmail.com
Wed Apr 22 09:33:32 CEST 2009

Thank you, Paolo.

I have read 17.22 and 17.24 sections of user guide. I think the problem of 
my calculations arises from "they contain a fractional translation that is 
incompatible with the FFT grid" since they change in unit cell volume. As a 
consquence, they do have different number of  k points.

[kyin at geohpclab results]$ grep 'number of k points=' *.out
temp-1.out:     number of k points=   16
temp-2.out:     number of k points=   16
temp-3.out:     number of k points=   16
temp-4.out:     number of k points=   32
temp-5.out:     number of k points=   32
temp-6.out:     number of k points=   32
temp-7.out:     number of k points=   32
temp-8.out:     number of k points=   16
temp-9.out:     number of k points=   16

 I think this missing of symmetries will not affect calculation of groud 
state energy. But if I use this scf calculation results to do phonon 
calculations, can I get correct phonon band assignment?

Kun Yin
Ph.D. Candidate
School of Earth Sciences and Engineering
Nanjing University
502 Geological Laboratory Building
22 Hankou Road
Nanjing 210093
P.R. China

email: kyin.cn at gmail.com
----- Original Message ----- 
From: "Paolo Giannozzi" <giannozz at democritos.it>
To: "PWSCF Forum" <pw_forum at pwscf.org>
Sent: Wednesday, April 22, 2009 2:46 PM
Subject: Re: [Pw_forum] improper symmetry analysis

> On Apr 22, 2009, at 8:33 , Kun Yin wrote:
>> I don't know how to fix this "improper symmetry analysis" problem.
>> Can you help me?
> item 1.22 of the Troubleshooting section of the user guide
> ---
> Paolo Giannozzi, Democritos and University of Udine, Italy
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> Pw_forum at pwscf.org
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