Toward Large-Scale AFQMC Calculations: Large Time Step Auxiliary-Field Quantum Monte Carlo

Autor(en)

Zoran Sukurma, Martin Schlipf, Moritz Humer, Amir Taheridehkordi, Georg Kresse

Abstrakt

We report modifications of the ph-AFQMC algorithm that allow the use of large time steps and reliable time step extrapolation. Our modified algorithm eliminates size-consistency errors present in the standard algorithm when large time steps are employed. We investigate various methods to approximate the exponential of the one-body operator within the AFQMC framework, distinctly demonstrating the superiority of Krylov methods over the conventional Taylor expansion. We assess various propagators within AFQMC and demonstrate that the Split-2 propagator is the optimal method, exhibiting the smallest time-step errors. For the HEAT set molecules, the time-step extrapolated energies deviate on average by only 0.19 kcal/mol from the accurate small time-step energies. For small water clusters, we obtain accurate complete basis-set binding energies using time-step extrapolation with a mean absolute error of 0.07 kcal/mol compared to CCSD(T). Using large time-step ph-AFQMC for the N2 dimer, we show that accurate bond lengths can be obtained while reducing CPU time by an order of magnitude.

Organisation(en)

Computergestützte Materialphysik

Externe Organisation(en)

VASP Software GmbH

Journal

Journal of Chemical Theory and Computation

Band

20

Seiten

4205–4217

Anzahl der Seiten

13

ISSN

1549-9618

DOI

https://doi.org/10.48550/arXiv.2403.02542

Publikationsdatum

05-2024

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/4225e3dd-2b3b-4b5c-bd05-8b51d424d3e8