[CPMD-list] problem with pair correlation function

[Axel Kohlmeyer]

On Sat, 19 Mar 2005, Younes Ansari wrote:

YA> Dear CPMD_list:

dear younes ansari,

YA>      I am still having problem using the CPMD trajectory to get the
YA>      pair correlation function of it.

unless you tell us, _what_ kind of a problem you have, 
there is little we can do. the procedure is standard
statistical mechanics textbook stuff. you loop over
atoms of type A and then loop over all atoms of type B,
calculate the distance to the closest image and create
a histogram from these values. now you do this for 
each timestep, and then normalize the resulting histogram
by dividing through the number of timesteps and the
volume of represent by each histogram slot (i.e. sphere shell)
times the number density of respective particles in your
simulation cell.

as pointed out before, most of the time you need to
adapt the code to your specific problem, so the code
is mostly written in a quick-and-dirty style, hence
the reluctance to share existing code.

also several MD packages include utility programs
for calculation of PCFs, but then you'd have to convert
your trajectory file to the native format of that package...

regards,
	axel.

YA>      Didn`t anybody do the same before which can help me through that.
YA> 
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-- 

=======================================================================
Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.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/
=======================================================================
If you make something idiot-proof, the universe creates a better idiot.