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   COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS
                   School of Computational Sciences
                           (CSI 898-Sec 001)
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Reliable Electronic Structure Calculations for Heavy Element Chemistry

                         Walter C. Ermler
         National Science Foundation, Arlington VA and
Computational Research on Materials Institute,University of Memphis

The computational methodology required for accurate quantum mechanical 
calculations of electronic structures and spectra of molecules 
containing heavy elements is presented.  Included is a description of 
how this technology is implemented in high performance software that is 
portable and scalable on massively parallel computer systems.  The 
computational intractability associated with the accurate treatment of 
polyatomic systems comprised of large numbers of electrons is currently 
a limiting factor in electronic structure calculations.  In such cases 
an attractive alternative is to represent a subset of the total number 
of atomic electrons (the core electrons) by a one-electron, 
radially-local operator called the pseudopotential.  If systems of 
interest contain heavy elements some form of the Dirac relativistic 
theory must be incorporated.  The present approach, based on the 
relativistic effective core potential (RECP) method of Lee, Ermler, 
Christiansen and Pitzer, formally reduces the number of electrons that 
must be explicitly described (the valence electrons) to a minimum while 
ensuring high accuracy in electronic spectra, ionization energies, 
spectroscopic constants, and other properties.  Valence electrons are 
treated using molecular orbital theory and electron correlation 
procedures, some of which incorporate spin-orbit coupling operators 
extracted from RECPs.  A series of applications are discussed including 
highly accurate calculations on Group 2 metal dimers, clusters of lead 
and bismuth iodide, a cesium oxide cluster, and metals encaged in 
buckminster fullerene.  Finally, results of an ongoing study of the 
f-electron spectra of the chlorides of americium are presented.
                
                Monday , February 2, 2004
                         4:30 pm
                Room 206, Science & Tech. I

Refreshments will be served at 4:15 PM.
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Find the schedule at http://www.scs.gmu.edu/lcdm/seminar/schedule.html