Quantum Monte Carlo calculations of A=8 nuclei

Journal Article · Sat Jul 01 04:00:00 EDT 2000 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PhysRevC.62.014001· OSTI ID:20216942

Wiringa, R B ^[1]; Pieper, Steven C ^[1]; Carlson, J ^[2]; Pandharipande, V R ^[3]

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1. Physics Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
2. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
3. Physics Department, University of Illinois at Urbana-Champaign, 1110 West Green St., Urbana, Illinois 61801 (United States)

We report quantum Monte Carlo calculations of ground and low-lying excited states for A=8 nuclei using a realistic Hamiltonian containing the Argonne v{sub 18} two-nucleon and Urbana IX three-nucleon potentials. The calculations begin with correlated eight-body wave functions that have a filled {alpha}-like core and four p-shell nucleons LS coupled to the appropriate (J{sup {pi}};T) quantum numbers for the state of interest. After optimization, these variational wave functions are used as input to a Green's function Monte Carlo calculation made with a new constrained path algorithm. We find that the Hamiltonian produces a {sup 8}Be ground state that is within 2 MeV of the experimental resonance, but the other eight-body energies are progressively worse as the neutron-proton asymmetry increases. The {sup 8}Li ground state is stable against breakup into subclusters, but the {sup 8}He ground state is not. The excited state spectra are in fair agreement with experiment, with both the single-particle behavior of {sup 8}He and {sup 8}Li and the collective rotational behavior of {sup 8}Be being reproduced. We also examine energy differences in the T=1,2 isomultiplets and isospin-mixing matrix elements in the excited states of {sup 8}Be. Finally, we present densities, momentum distributions, and studies of the intrinsic shapes of these nuclei, with {sup 8}Be exhibiting a definite 2{alpha} cluster structure. (c) 2000 The American Physical Society.

• OSTI ID: 20216942
• Journal Information: Physical Review. C, Nuclear Physics, Journal Name: Physical Review. C, Nuclear Physics Journal Issue: 1 Vol. 62; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BERYLLIUM 8
CLUSTER MODEL
EXCITED STATES
GROUND STATES
HELIUM 8
ISOSPIN
LITHIUM 8
MONTE CARLO METHOD
NUCLEAR PROPERTIES
THEORETICAL DATA
WAVE FUNCTIONS