[Wien] PLEASE HELP:- Completely flat ELNES!

[a s]

Hello Folks

I am running Wien2K_03 on a Pentium 4 2GHz machine with a Red hat Linux 7.3 
operating system.

The purpose of my calculations is to simulate ELNES of graphite with a low 
concentration of individual C atoms substitutionally replaced by N atoms.

In order to do this simulation, I have constructed a supercell consisting of 
8 atoms, with one C atom replaced with a N atom.  The entire calculation 
runs perfectly from start to finish, providing a graphite-like carbon ELNES, 
as expected.

When I increase the number of cells in the x, y and z directions in the 
supercell program, again, the entire calculation runs perfectly from start 
to finish, providing a graphite-like carbon ELNES, as expected.

However, when I increase the number of cells in the x, y and z directions 
further, so that the struct file consists of 23 atoms, the resultant ELNES 
is completely flat!  I absolutely do not change *any parameters* from the 
previous simulations (other than a larger no of atoms in the struct file).

When I examine the telnes file of the flat ELNES, *below 0 eV*, it consists 
of the energy followed by 5 columns of zeros,i.e.

-2.5    0     0     0     0     0

*Above 0 eV*, it consists of the energy followed by a row of question marks


This problem is clearly related to number of cells (i.e. the size).  I have 
already tried the following things:

1.  I have followed precisely the instructions detailed in the FAQ, 
“Converting cases from pre-WIEN2k_03 style to WIEN2k_03 style (supporting 
more than 99 atoms/cell)”

2.  I have followed precisely the instructions detailed in the ML, that 
allows ELNES to be calculated for big systems, i.e.

I changed in SRC_lapw2/l2main.F :
100   FORMAT('inequivalent atom number',I3,' number ',I2,' total ',I2)
to
100   FORMAT('inequivalent atom number',I3,' number ',I2,' total ',I3)


I also changed in SRC_telnes/lecture.f :
100  FORMAT(25X,I2,8X,I2,7X,I2)
to
100  FORMAT(24X,I3,8X,I2,7X,I3)

Please help!



Kindest regards

_________________________________________________________________
Be the first to hear what's new at MSN - sign up to our free newsletters! 
http://www.msn.co.uk/newsletters