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Dear all,

This is more of a scientific question than a technical one - I hope this 
is the right place to ask.

I'm new to the CCP4 bundle. So far I've only used the AREAIMOL tool, 
which determines the accessible surface area of a system. My system is 
an irregular periodic slab and so I have used the following options:

    SMODE IMOL
    TRANS
    PROBE 0.75
    OUTPUT
    END

I have used such a small probe sphere radius because it's half of the 
first peak in the radial distribution function, that is, more or less 
half of the average first nearest-neighbor distance.

I'm doing this because my slab being amorphous I want to have a 
systematic and unambiguous way of determining the number of surface 
atoms. Using the settings above, AREAIMOL produces a number of surface 
atoms in good agreement with a naive visual interpretation of the 
structure, which feels right.

My question is if this is a sound approach and what alternative criteria 
for computing the number of surface atoms are available/used by the 
community.

Many thanks,
Miguel
-- 
*Dr. Miguel Caro*
/Postdoctoral researcher/
Department of Electrical Engineering and Automation,
and COMP Centre of Excellence in Computational Nanoscience
Aalto University, Finland
Personal email: *[log in to unmask]*
Work: *[log in to unmask]*
Website: http://mcaroba.dyndns.org