[CPMD-list] Density Cubefile

[Axel Kohlmeyer]

>>> "BS" == Balasubramanian Sundaram <Dr.> writes:


BS> Dear All,
BS>    I am getting the RHO_TOT.cube file for a bulk system (with 3-d PBC) 
BS> in liquid state through the PROP keyword. I am able to understand the 
BS> header portion of this file, as containing the origin (lowerleft corner 
BS> in the source code), the grid spacing, the ion coordinates, followed by
BS> the density values in 2-column format. (z is the innermost loop, y is 
BS> the middle one, and x is the outermost loop).

hello bala,

BS>    I need help in figuring out the actual x,y,z coordinates of each of 
BS> the grid point. And how the charge density grid is mapped onto the ion
BS> coordinates.

to get those you only need to fgure out the x-, y-, and z counting index
for each point and then multiply with the respective grid vectors (lines
4-6) and finally add those three vectors. this is the standard gaussian
style cube file format (although it looks a bit different). the version
of the code in cpmd 3.7 has some problems on some machines. you may want
to try using RHOOUT and cpmd2cube (which has other problems) as an 
alternative route to get to the same result.

both problems mentioned have been fixed in the current development
versions, which are scheduled to be relased in the near future.

BS>    Specifically I am trying to reproduce the result of Laasonen, Sprik
BS> and
BS> Parrinello, JCP (1993) to obtain the molecular dipole moment of water
BS> molecules
BS> in liquid water, as a learning exercise. I realize that it is possible

if i am not totally mistaken, this has also been implemented in the 
development version of cpmd. so you will have a nice opportunity to
cross-check your results.

take care,
     axel.
BS> to 
BS> get this information from the Wannier+Ion centers as well, but I need to
BS> obtain
BS> it from the charge density+Ion Centers.

BS> Thanks!

BS> Best Regards,
BS> Bala
BS> _______________________________________________
BS> CPMD-list mailing list
BS> CPMD-list at cpmd.org
BS> http://www.cpmd.org/mailman/listinfo/cpmd-list



--

=======================================================================
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.