Toward Large-Scale AFQMC Calculations: Large Time Step Auxiliary-Field Quantum Monte Carlo
- Author(s)
- Zoran Sukurma, Martin Schlipf, Moritz Humer, Amir Taheridehkordi, Georg Kresse
- Abstract
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(s)
- Computational Materials Physics
- External organisation(s)
- VASP Software GmbH
- Journal
- Journal of Chemical Theory and Computation
- Volume
- 20
- Pages
- 4205–4217
- No. of pages
- 13
- ISSN
- 1549-9618
- DOI
- https://doi.org/10.48550/arXiv.2403.02542
- Publication date
- 05-2024
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103006 Chemical physics, 103043 Computational physics
- ASJC Scopus subject areas
- Computer Science Applications, Physical and Theoretical Chemistry
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/toward-largescale-afqmc-calculations-large-time-step-auxiliaryfield-quantum-monte-carlo(4225e3dd-2b3b-4b5c-bd05-8b51d424d3e8).html