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Accueil > Séminaires > 2015

How to implement perturbation theories in the FCIQMC framework ?

Guillaume Jeanmairet, MPI for Solid State Research (Stuttgart, Allemagne)

Salle de séminaire IRSAMC, Jeudi 12 Novembre, 14h - 15h

Full configuration interaction quantum Monte Carlo is a method to simulate many-electron systems stochastically. It propagates the imaginary-time Schrödinger equation using a population dynamics of walkers. These walkers are living in the Slater determinant space, and carry a sign. Alavi et al have shown that this method converges to FCI results[1] without a prior information of the nodal structure of the wavefunction. This method has been applied with success to various molecular systems and solids. However bigger systems are still out of reach. To increase the applicability of the method we are implementing perturbation theories (and in particular the recently proposed MR-LCC method[2]) within the FCIQMC framework. This requires to keep track of several population of walkers, one sampling the zero order wavefunction, and other sampling the first order wavefunction.

[1] G. H. Booth, A. J. W. Thom, A.Alavi, J. Chem. Phys., 2009, 131, 054106.
[2] S. Sharma and A. Alavi, J. Chem. Phys., 2015, 143, 102815.