2007/05/19 by W. A. Al-Saidi, Shiwei Zhang, Henry Krakauer · 1 citation
Engineering · Mathematics · Physics and Astronomy · #Advancements in Semiconductor Devices and Circuit Design #Field (mathematics) #Mathematics #Monte Carlo method #Physics #Quantum Monte Carlo #Quantum and electron transport phenomena #Quantum many-body systems #Statistical physics #Statistics #cond-mat.str-el #physics.chem-ph #physics.comp-ph
paper · pdf · doi:10.1063/1.2770707
published as JCP, 127, 144101 (2007). · 8 pages, 3 figures and 3 tables. Submitted to JCP
arxiv created 2007/05/19 · openalex publication_date 2007/10/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Bond stretching mimics different levels of electron correlation and provides a challenging test bed for approximate many-body computational methods. Using the recently developed phaseless auxiliary-field quantum Monte Carlo (AF QMC) method, we examine bond stretching in the well-studied molecules BH and N(2) and in the H(50) chain. To control the sign/phase problem, the phaseless AF QMC method constrains the paths in the auxiliary-field path integrals with an approximate phase condition that depends on a trial wave function. With single Slater determinants from unrestricted Hartree-Fock as trial wave function, the phaseless AF QMC method generally gives better overall accuracy and a more uniform behavior than the coupled cluster CCSD(T) method in mapping the potential-energy curve. In both BH and N(2), we also study the use of multiple-determinant trial wave functions from multiconfiguration self-consistent-field calculations. The increase in computational cost versus the gain in statistical and systematic accuracy are examined. With such trial wave functions, excellent results are obtained across the entire region between equilibrium and the dissociation limit.