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           COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
                             College of Science
                      (CDS Department CSI 898-Sec 001)
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          "Ab initio auxiliary-field Quantum Monte Carlo"

                           Wissam Al-Saidi
         Physics Department, Cornell University, Ithaca, NY

I will present the auxiliary-field quantum Monte Carlo (AF QMC) method
for many-body systems, and in particular for realistic electronic
Hamiltonians. The presentation will be pedagogical and a previous
knowledge of ab initio methods or quantum Monte Carlo will be helpful
but not required. In the AF QMC method, the ground state energy is
obtained through a linear superposition of independent-particle
solutions interacting through fluctuating external fields. This
process is realized as a random walk in Slater determinant space. The
QMC sign/phase problem is controlled using a trial wave function from
Hartree-Fock or density functional calculations. The AF QMC method
interfaces naturally with standard electronic structure approaches and
can import their technology into a many-body QMC framework. Results
obtained on equilibrium properties of atoms and molecules as well as
Born-Oppenheimer potential energy surfaces showed excellent agreement
with the best of quantum chemistry methods and/or experiment.

                          Febraury 5, 4:30 pm
                   Room 301, Research I, Fairfax Campus

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