Dear PyMol Experts,
I would like to use pymol to visualize a periodic structure
and show isosurface of charge density calculated from a LDA
code. I have the charge density on a regular grid (in
fractional coordinates).
I am very new in pymol and not sure if it is possible to do
some of the following tasks:
1. How can I get my density data into pymol to do isosurface
plot?  I never used xplor map files before and I coudn't
find information about the file format, etc??
2. Is it possible to have a plane cutting the isosurface
(to show a 2D  contour plot on a plane in the crystal)?
I noticed that "gopenmol" does what I ask above but I like
python and therefore I want to do these by using  pymol!
Any help or suggestions would be appreciated very much.
PS: one more question about CGO? I noticed that we can
do spheres and cylinders? What about an "arrow" object?
If I want to show a magnetic structure, how can I include the
spin vectors on atoms  in pymol?  Is there a anything available
for arrow?
Dr. Taner Yildirim, Ph.D. Physicist, Condensed Matter Science Group,                     NIST Center for Neutron Research,
PHONE: 301-975-6228     National Institute of Standards & Technology
FAX  : 301-921-9847                      Gaithersburg, MD 20899-8562
Web  :