Long LDOS calculation times with simple structures

[David Eustace <daveus@chem.gla.ac.uk>]

Hello all,

At present I am trying to run LDOS calculations on simple rock salt 
structures to establish the parameters I want to use on more complicated 
materials. I'm having a bit of a problem with the length of time these 
calculations take. We run feff 8.1 on an alpha dec computer, with a dual 
processors. I'm not looking to upgrade the system specs, I'm referring to 
the time these calculations take relative to others we run (they take two 
or three days longer).

After running an initial calculation with all control modules on, which I'm 
not really concerned about, I vary my LDOS parameters then run with only 
the second module.

To get decent resolution on my plots, I have reduced the energy range over 
which I'm calculating the LDOS, but still require a very large number of 
atoms to obtain fine structure (about 300-450). This makes my calculations 
take a long time (typically between 3 and 5 days), although they have 
started yielding . Typical detailed calculations on our system usually take 
1-2 days.

I reckon because I'm using a simple structure, good resolution requires 
long scattering lengths. If I'm wrong, please let me know. I use the FMS 
card to define scattering length, I omit the SCF card.

I was wondering if there was any way of making these calculations go 
faster? All I'm looking to obtain is the LDOS, i.e. the rholnn.dat 
(ldosnn.dat on feff 8.2) files. Is it possible to 'omit' other functions 
performed by the second control module? (I only run the LDOS and FMS cards 
in my input file).

I hope these are reasonable questions, many thanks for any help you can 
give me,

David Eustace