This page describes transforming Quantum Espresso charge density output 
into AViz input for a model of nanotube electronic density.
Original nanotube coordinates - Polina Pine
Quantum Espresso runs - Valentino Cooper at Oakridge 
Technion compilation -Dastien Grosso with help from Julia and Arik Landau -
will be placed on-site soon 
AViz conversion - Joan Adler - described below
Recombination of  4 quarter circles of data into a ring

Copy nanotube_0.0.charge to a new file 
called fort.4 and remove all lines up to the end of the list of original 
atomic locations, 28 of them in this case. 

Work out from here the total number of density points.
(see this extract from qe literature to understand the 
.charge format structure.
Edit convert.f with the total number of atoms and 
a comment line.

Compile  convert.f  with 
f77 convert.f -o convert.ex
run the file convert.ex

You will then have a fort.7 file that can be renamed to e.g.
and used in AViz.