Selected Configuration Interaction expansions for quantum Monte Carlo calculations and stochastic secondorder multi-reference perturbation theory methods (MRPT2)

Event Sponsor: 
Materials Science Division Seminar
Start Date: 
Feb 23 2017 - 11:00am
Building/Room: 
Building 223/Room S105
Location: 
Argonne National Laboratory
Speaker(s): 
Michel Caffarel
Host: 
University of Toulouse, France

In this talk I first discuss our recent use of perturbatively selected configuration interaction expansions for building accurate trial wavefunctions for diffusion Monte Carlo (DMC) calculations. I argue that by using such expansions an improved control of the fixed-node error is possible. Second, I present a newly introduced stochastic approach to compute very efficiently the second-order energy correction of multireference perturbation theories (MRPT2, CASPT2, NEVPT2,...).