[Wien] problems with supercells

[Sergio Galindo Torres]

I'm studying the band structure of the Si crystal with Al impurities qith 
Wien 98.7 package and I have tree questions about it:

The last week i send a mail asking for a problem that I have in the SCF 
cycle. It stoped after a few iterations. The solution that you gave me was 
to remove the broyd and scf files, change the broyden factor from 0.4 to 0.1 
and run x dstart and run_lapw again. The Scf cycle then stoped after just 
one iteration and the convergence wasn't reached yet. Again no error 
messages were displayed in any of the error and ouput files. So, what can i 
do?

My other question is conserning the physical problem: In the structure file, 
How do I set the RMT fpr the Si and the Al?. I heard that there is a problem 
with the difference of the atomic radii when one works the impurity problem 
in a LAPW based program.

My last question is about performance of the calculation. I work with a 
supercell of 64 atoms and it takes 3 days for just one iteration (even when 
I work in a good platform: Intel Xeon 1.5GHz with 2GB RAM). I compiled the 
program with the -O3 option for the f77 compiler and force an iterative 
diagonalization with the -it flag in the run_lapw. Should I reduce the size 
of the matrices in the Global parameters?. You also advised in the manual to 
compile with and option depending of the particular arquitecture. What is 
this option for the platform that i just mentioned.

Thanks

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