对“~（40）Ca的重要性截断无核壳模型从头算研究”一文的评论

Ab Initio No Core Shell Model - Recent Results and Further Prospects

There has been significant recent progress in solving the long-standing problems of how nuclear shell structure and collective motion emerge from underlying microscopic inter-nucleon interactions. We review a selection of recent significant results within the ab initio No Core Shell Model (NCSM) closely tied to three major factors enabling this progress: (1) improved nuclear interactions that accurately describe the experimental two-nucleon and three-nucleon interaction data; (2) advances in algorithms to simulate the quantum many-body problem with strong interactions; and (3) continued rapid …

Converged ab initio calculations of heavy nuclei

We propose a novel storage scheme for three-nucleon (3N) interaction matrix elements relevant for the normal-ordered two-body approximation used extensively in ab initio calculations of atomic nuclei. This scheme reduces the required memory by approximately two orders of magnitude, which allows the generation of 3N interaction matrix elements with the standard truncation of $E_{\rm 3max}=28$, well beyond the previous limit of 18. We demonstrate that this is sufficient to obtain the ground-state energy of $^{132}$Sn converged to within a few MeV with respect to the $E_{\rm 3max}$ truncation.In …

偶氧同位素手性2 + 3核子相互作用的从头计算

Ab Initio Calculations of Even Oxygen Isotopes with Chiral Two- Plus Three-Nucleon Interactions

基于量子化学中的广义Wick定理，采用多参考形式，建立了开壳层核的介质内相似重整化群（IM-SRG）.由此产生的多参考IM-SRG（MR-IM-SRG）是用来执行第一从头算研究，甚至氧同位素与手性NN和3 N哈密顿量，从质子到中子滴线。我们得到了一个很好的再现实验基态能量与量化的不确定性，这是验证的结果，从重要性截断无核壳模型和耦合簇方法。概念上不同的多体方法和实验之间的协议突出了当前手性两个和三个核子相互作用的预测能力，并建立MR-IM-SRG作为一个有前途的新工具，从头计算远离壳层封闭的中等质量的核。

大尺度组态相互作用方法的重要性截断

Importance Truncation for Large-Scale Configuration Interaction Approaches

我们引入了一个迭代的重要性截断计划，其目的是通过先验选择物理上最相关的基态来降低组态相互作用方法的模型空间的维数。使用来自多组态微扰理论与重要性阈值相结合的重要性措施，我们构建了一个模型空间优化的一个给定的哈密顿量的单个本征态的描述。我们详细讨论了各种技术方面和改进的重要性截断，如微扰校正排除的基态，阈值外推技术，和不同的迭代模型空间更新计划。我们在无核壳模型（NCSM）的上下文中应用重要性截断的思想，对核的基态进行从头计算。在一系列的基准计算封闭和开放壳层核O-16，我们比较的基态能量的重要性截断NCSM完整的NCSM。所有的计算表明，一个很好的协议的重要性截断和充分NCSM的所有情况下，后者是可行的。结果表明，重要性截断的NCSM在保留了完整NCSM的大部分优点的同时，提供了更大的N_max*hbar*Omega空间和更重的核.用这种方法，我们能够对C-12和O-16等核进行重要截断的NCSM计算，直到N_max=22。

Natural orbitals for the ab initio no-core configuration interaction approach

Ab initio no-core configuration interaction (NCCI) calculations for the nuclear many-body problem have traditionally relied upon an antisymmetrized product (Slater determinant) basis built from harmonic oscillator orbitals. The accuracy of such calculations is limited by the finite dimensions which are computationally feasible for the truncated many-body space. We therefore seek to improve the accuracy obtained for a given basis size by optimizing the choice of single-particle orbitals. Natural orbitals, which diagonalize the one-body density matrix, provide a basis which maximizes the occupat…

Light Neutron-Rich Hypernuclei from the Importance-Truncated No-Core Shell Model

We explore the systematics of ground-state and excitation energies in singly-strange hypernuclei throughout the helium and lithium isotopic chains --- from $^5_Λ$He to $^{11}_Λ$He and from $^7_Λ$Li to $^{12}_Λ$Li --- in the ab initio no-core shell model with importance truncation. All calculations are based on two- and three-baryon interaction from chiral effective field theory and we employ a similarity renormalization group transformation consistently up to the three-baryon level to improve the model-space convergence. While the absolute energies of hypernuclear states show a systematic vari…

Combining symmetry breaking and restoration with configuration interaction: a highly accurate many-body scheme applied to the pairing Hamiltonian

Background: Ab initio many-body methods have been developed over the past ten years to address mid-mass nuclei... As progress in the design of inter-nucleon interactions is made, further efforts must be made to tailor many-body methods. Methods: We formulate a truncated configuration interaction method that consists of diagonalizing the Hamiltonian in a highly truncated subspace of the total N-body Hilbert space. The reduced Hilbert space is generated via the particle-number projected BCS state along with projected seniority-zero two and four quasi-particle excitations. Furthermore, the extent…

Core-polarization effects and effective charges in O and Ni isotopes from chiral interactions

Most nuclear structure calculations, even for full configuration interaction approaches, are performed within truncated model spaces. These require consistent transformations of the Hamiltonian and operators to account for the missing physics beyond the active space, so that several recent efforts have been devoted to find compatible derivations of the effective operators. The effective charges employed in the shell-model calculations, and fitted to reproduce experimental data, can be seen as the phenomenological counterpart of such renormalization for electromagnetic operators. Here, we make …