Self-Refinement of Auxiliary-Field Quantum Monte Carlo via Non-Orthogonal Configuration Interaction

Autor(en)

Zoran Sukurma, Martin Schlipf, Georg Kresse

Abstrakt

For optimal accuracy, auxiliary-field quantum Monte Carlo (AFQMC) requires trial states consisting of multiple Slater determinants. We develop an efficient algorithm to select the determinants from an AFQMC random walk eliminating the need for other methods. When determinants contribute significantly to the nonorthogonal configuration interaction energy, we include them in the trial state. These refined trial wave functions significantly reduce the phaseless bias and sampling variance of the local energy estimator. With 100 to 200 determinants, we lower the error of AFQMC by up to a factor of 10 for second-row elements that are not accurately described with a Hartree-Fock trial wave function. For the HEAT set, we improve the average error to within chemical accuracy. For benzene, the largest studied system, we reduce AFQMC error by 80% with 214 Slater determinants and find a 10-fold increase of the time to solution. We show that phaseless errors prevail in systems with static correlation or strong spin contamination. For such systems, improved trial states enable stable free-projection AFQMC calculations, achieving chemical accuracy even in the strongly correlated regime.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

VASP Software GmbH

Journal

Journal of Chemical Theory and Computation

Band

21

Seiten

4481-4493

Anzahl der Seiten

13

ISSN

1549-9618

DOI

https://doi.org/10.48550/arXiv.2501.12765

Publikationsdatum

05-2025

Peer-reviewed

Ja

ÖFOS 2012

103006 Chemische Physik, 103043 Computational Physics

ASJC Scopus Sachgebiete

Computer Science Applications, Physical and Theoretical Chemistry

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/9be57d71-b475-4bcf-983c-536ff7eb117d