Si(111) 7x7 reconstruction geometry



 Dear colleagues,
 Does anyone knows where I can get a z-matrix or Cartesian coordinate for
 a cluster of silicon atoms three layers deep from the Si(111) 7x7
 reconstructed surface?  I would appreciate an experimental/ theoretical
 or combined reference.  Is there a database that would supply surface
 unit cells geometries?
 Thank you very much.  I will summarize the answers.
     Cherif
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   Chérif F. Matta,
   Theoretical/Computational Chemist,
   Polanyi Research Group,
   Lash Miller Chemical Laboratories,
   Chemistry Department,
   University of Toronto,
   80 St. George Street (Room 261),
   Toronto, Ontario, Canada M5S 1A1
   ..................................
   Telephone:      (416) 978 - 3625
   Cellular:       (416) 996 - 2444
   Fax:            (416) 978 - 7580
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