[CPMD-list] cpmd2cube is not working properly

[Axel Kohlmeyer]

On Mon, 22 Mar 2004, Audrius Alkauskas wrote:

AA> Hello
AA> 
AA> I have problems with cpmd2cube.
AA> 
AA> It was compiled with the same options as cpmd (intel compiler V8 and the 
AA> MKL library mkl60).
AA> 
AA> If I run just
AA> 
AA> cpmd2cube -dens DENSITY
AA> 
AA> I get negative densities sometimes, like:
AA> 

hi,

this is to be expected to some degree. 

the DENSITY file stores the density in g-space and cpmd2cube
does the fourier transform back to real space. since you did not use
an infinitely large grid in g-space, some noise (= negative density 
values) is to be expected.

on top of that, the cpmd2cube version, that you are using, uses only 
half the grid points in each direction, for the backward fft than your 
simulation used. which makes gives you nice small but _much_ noisier
cube files.

this has been fixed recently in the development tree 
and will (hopefully) be released on cpmd.org soon.

axel kohlmeyer.


AA> 0.93180E-09  0.63883E-05 -0.22307E-04 -0.87219E-06  0.18121E-04 -0.95568E-04
AA> 0.92963E-04  0.82842E-05 -0.14464E-04  0.77029E-04 -0.73099E-04 -0.14575E-04
AA> -0.49348E-04  0.18838E-05  0.37324E-04  0.47154E-04  0.29103E-04 
AA> -0.27480E-04
AA> -0.26917E-05 -0.73552E-04  0.40827E-05  0.27440E-04 -0.21607E-04  
AA> 0.80581E-04
AA> -0.34046E-04 -0.10135E-04  0.36526E-04 -0.53954E-04  0.53740E-04 
AA> -0.89581E-04
AA> 
AA> which I suppose should not be the case.
AA> 
AA> But I also tried to run to read the data with double precision, like:
AA> 
AA> cpmd2cube -dens -double DENSITY
AA> 
AA> and I got the messsage:
AA> 
AA>  > .read input file ... forrtl: severe (67): input statement requires 
AA> too much data, unit 99, file (...)/DENSITY
AA>  > Image                       PC               Routine                  
AA> Line        Source
AA>  > cpmd2cube       0809C82D   Unknown              Unknown  Unknown
AA> .....
AA>  > Stack trace terminated abnormally.
AA> 
AA> What is wrong?
AA> 
AA> Regards
AA> 
AA> Audrius Alkauskas
AA> 
AA> _______________________________________________
AA> CPMD-list mailing list
AA> CPMD-list at cpmd.org
AA> http://www.cpmd.org/mailman/listinfo/cpmd-list
AA> 
AA> 

-- 


=======================================================================
Dr. Axel Kohlmeyer                        e-mail: axel.kohlmeyer at rub.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
=======================================================================