Fully-microscopic No-core Shell Model (NCSM) calculations of all stable s and p shell nuclei are used to determine a realistic N N interaction, JISP16, describing not only the two-nucleon data but the binding energies and spectra of nuclei with A ≤ 16 as well. The JISP16 interaction, providing rapid convergence of the NCSM calculations, is obtained in an ab exitu approach by phase-equivalent transformations of the JISP6 N N interaction. To complement the successful but computationally intensive 'ab initio' No-core Shell Model (NCSM) [1], we introduce the 'ab exitu' NCSM. While the former has proven very successful for light nuclei when one includes three-body (N N N ) forces [2,3], the computational complexity motivates us to introduce an approach that simultaneously minimizes N N N forces while providing more rapid convergence with a pure nucleon-nucleon (N N ) force. We invoke directly an end-goal of nuclear theory (hence the term 'ab exitu'), a successful description of nuclear properties, including the available N N data, to develop a new class of N N potentials that provide accurate descriptions of a broad range of nuclear data.
PACSTo achieve this, we form a union of two recent techniques -the J-matrix inverse scattering [4,5,6] and the NCSM [1]. A major ingredient of our approach is the form of the N N interaction (a small matrix in the oscillator basis), which is chosen to provide rapid convergence of manybody observables within the NCSM. Indeed, we show below that results up through A = 16 obtained directly with the bare interaction (one that accurately describes the N N data) are close to those obtained with the effective interaction and are very useful to establish the confidence region for the binding energy.Since this is a departure from the more traditional approach, we motivate our development with observations concerning the successful ab initio approaches to light nuclei. Indeed several promising microscopic approaches have been introduced and tested extensively with realistic N N interactions (see [7] and references therein) and with realistic N N + N N N interactions [8,2,3]. Progress towards heavier nuclei appears limited only by scientific manpower and by available computers. However, all approaches face the exponentially rising computational complexity inherent in the quantum many-body problem with increasing particle number and novel schemes are needed to minimize the computational burden without sacrificing realism and precision.The earliest and most successful in reaching nuclei beyond A = 4 is the Green's-function Monte Carlo (GFMC) approach [8] whose power has been used to determine a sequence of everimproving N N N interactions [8,9,10], in conjunction with highly precise N N interactions [11] that 1
The nucleon-nucleon interaction is constructed by means of the J-matrix version of inverse scattering theory. Ambiguities of the interaction are eliminated by postulating tridiagonal and quasi-tridiagonal forms of the potential matrix in the oscillator basis in uncoupled and coupled waves, respectively. The obtained interaction is very accurate in reproducing the N N scattering data and deuteron properties. The interaction is used in the no-core shell model calculations of 3 H and 4 He nuclei. The resulting binding energies of 3 H and 4 He are very close to experimental values.
Nucleon-nucleon (NN) phase shifts and the spectroscopy of $A \le 6$ nuclei
are successfully described by an inverse scattering potential that is separable
with oscillator form factors.Comment: 4 pages, 1 figure, 13 table
The relation between the R-and P-matrix approaches and the harmonic oscillator representation of the quantum scattering theory (J-matrix method) is discussed. We construct a discrete analogue of the P-matrix that is shown to be equivalent to the usual P-matrix in the quasiclassical limit. A definition of the natural channel radius is introduced. As a result, it is shown to be possible to use a well-developed technique of R-and P-matrix theory for calculation of resonant states characteristics, scattering phase shifts, etc., in the approaches based on harmonic oscillator expansions, e.g., in nuclear shell-model calculations. The P-matrix is used also for formulation of the method of treating Coulomb asymptotics in the scattering theory in oscillator representation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.