[CPMD-list] EWALD SUM not equal in real and Q-space

[Juerg Hutter]

Hi

I can't reproduce this problem. Could you post an input
for a system (as small as possible) where this error
occurs?

Juerg

----------------------------------------------------------
Juerg Hutter                   Phone : ++41 1 635 4491
Physical Chemistry Institute   FAX   : ++41 1 635 6838
University of Zurich           E-mail: hutter at pci.unizh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
----------------------------------------------------------


On Fri, 9 Aug 2002, Shiwu Gao wrote:

> Hi,
> 
> I got a trouble in running CPMD with the Vanderbildt uspp, 
> which I generated myself. The program stops and complains that
> the Ewald sum does not equal in real and Fourier Q-space, 
> 
> Typical error message looks like this 
> 
>   ****************************************************************
> 
>  CPU TIME FOR WAVEFUNCTION INITIALIZATION:           8.73 SECONDS
>  ***    RWFOPT| THE NEW SIZE OF THE PROGRAM IS   13844 kBYTES ***
>  EWALD SUM IN REAL SPACE OVER  5* 5* 5 CELLS
> IN FOURIER SPACE:                               360.000005713858
> IN REAL SPACE:                                  359.999999999984
> 
>  *****************************************************************
> 
> Note the charge should be 360 in this case. Tested many uspp's including
> the potential included in the latest uspp package. All have the same 
> problem. Note that the sum in real space is usually OK with an error 
> less than 10^-10, while the error in Q-space is large, 10^-5--10^-6. 
> 
> Has anybody met this problem with uspp? What is the way out of it? 
> 
> Thanks in advance,
> 
> Shiwu Gao
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