[Pw_forum] improper symmetry analysis

[YIN Kun]

Thanks a lot for explaining, Lorenzo. 

Perhaps using "right" and "wrong" is not suitable to describe problem. They just meant the symmetry which I intend to get or not. Follow your instructions, I get the "right" symmetry which I intend to. I think I know "how" to solve this problem now. And I have to spend more time to learn about FFT grid so as to totally understand "why" doing this way. 

L & P, Thank you again!
 
----- Original Message ----- 
From: "Paolo Giannozzi" <giannozz at democritos.it>
To: "PWSCF Forum" <pw_forum at pwscf.org>
Sent: Wednesday, April 22, 2009 6:34 PM
Subject: Re: [Pw_forum] improper symmetry analysis


> Lorenzo Paulatto wrote:
> 
>> If I remember correctly symmetry is applied only on the FFT grid, the  
>> dimensions of the smooth grid should not matter.
> 
> you remeber correctly, but actuyally there is no ]strong reason for
> such choice: the part of the charge density that has to be symmetrized
> is calculated in the smooth grid
> 
>> Likely they are too small with respect to what your cutoffs requires!
> 
> one can try to reduce a little bit the fft dimensions, but success is
> not guaranteed! anyway the code should loudly complain
> 
> P.
> -- 
> Paolo Giannozzi, Democritos and University of Udine, Italy
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