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Nuclear Theory·nucl-th

Wednesday·February 21, 2024

7 papers—5 primary·2 cross-listed

All7Primary5Cross-lists2
  1. 06

    [Submitted on 20 Feb 2024] (cross-list from hep-lat)

    Lüscher equation with long-range forces

    Rishabh Bubna🇩🇪 · Hans-Werner Hammer🇩🇪 · Fabian Müller🇩🇪 · Jin-Yi Pang🇨🇳 · Akaki Rusetsky🇩🇪 · Jia-Jun Wu🇨🇳

    We derive the modified Lüscher equation in the presence of the long-range force caused by the exchange of a light particle. It is shown that the use of this equation enables one to circumvent the problems related to the strong partial-wave mixing and the t-channel sub-threshold singularities. It is also demonstrated that the present method is intrinsically linked to the so-called modified effective-range expansion (MERE) in the infinite volume. A detailed comparison with the two recently proposed alternative approaches is provided.

    Comments:
    28 pages, 4 figures
    Subjects:
    High Energy Physics — Lattice (hep-lat); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
    arXiv:
    2402.12985 [pdf]
    JHEP(2024)·43 citations
  2. 07

    [Submitted on 20 Feb 2024] (cross-list from physics.chem-ph)

    Go Green: Selected Configuration Interaction as a More Sustainable Alternative for High Accuracy

    Pierre-François Loos · Yann Damour · Abdallah Ammar · Michel Caffarel · Fábris Kossoski · Anthony Scemama

    Recently, a new distributed implementation of the full configuration interaction (FCI) method has been reported [Gao et al. J. Chem Theory Comput. 2024, 20, 1185]. Thanks to a hybrid parallelization scheme, the authors were able to compute the exact energy of propane (\ce{C3H8}) in the minimal basis STO-3G. This formidable task involves handling an active space of 26 electrons in 23 orbitals or a Hilbert space of \SI{1.3d12} determinants. This is, by far, the largest FCI calculation reported to date. Here, we illustrate how, from a general point of view, selected configuration interaction (SCI) can achieve microhartree accuracy at a fraction of the computational and memory cost, via a sparse exploration of the FCI space. The present SCI calculations are performed with the \textit{Configuration Interaction using a Perturbative Selection made Iteratively} (CIPSI) algorithm, as implemented in a determinant-driven way in the \textsc{quantum package} software. The present study reinforces the common wisdom that among the exponentially large number of determinants in the FCI space, only a tiny fraction of them significantly contribute to the energy. More importantly, it demonstrates the feasibility of achieving comparable accuracy using more reasonable and sustainable computational resources, hence reducing the ever-growing carbon footprint of computational chemistry.

    Comments:
    5 pages, 2 figures (supporting information available)
    Subjects:
    physics.chem-ph (physics.chem-ph); cond-mat.mtrl-sci (cond-mat.mtrl-sci); Strongly Correlated Electrons (cond-mat.str-el); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
    arXiv:
    2402.13111 [pdf]
    2 citations

Affiliations

first authorsco-authorsvia INSPIRE