Systematic improvement of diffusion Monte Carlo nodal surfaces through multi-determinant trial wavefunctions for molecules and solids (PC)

Dr. Anouar Benali (Computational Scientist, Argonne National Laboratory, IL, USA)

"In the past decade, fixed-node diffusion Monte Carlo using a single determinant Slater-Jastrow trial wavefunction as proven to systematically reproduce (within 0.5-10Kcal/mol) the energies of a wide range of molecules and solids. While it has been demonstrated for molecular systems that the path to chemical accuracy (<1Kcal/mol) can be realized by improving the nodal surface using for example multi-determinant trial wavefunctions generated with MCSCF or Selected CI. Reaching the same level of accuracy for large molecules or solids at the thermodynamic limit has proven harder due to the exponential scaling of these wavefunction generation methods. In this talk, we will present multiple methods to generate multi-Slater determinant trial wavefunctions and compare their accuracy/cost ratio for various sizes of molecules and solids."

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