Quantum Monte Carlo calculations of {Alpha} = 8 nuclei.

Journal Article · Sat Jul 01 04:00:00 EDT 2000 · Phys. Rev. C

DOI:https://doi.org/10.1103/PhysRevC.62.014001· OSTI ID:942847

Wiringa, R B; Pieper, S C; Carlson, J; Pandharipande, V R; LANL,

We report quantum Monte Carlo calculations of ground and low-lying excited states for {Alpha}=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.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; NSF
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 942847
• Report Number(s): ANL/PHY/JA-35213
• Journal Information: Phys. Rev. C, Journal Name: Phys. Rev. C Journal Issue: 1 ; Jul. 2000 Vol. 62; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
EXCITED STATES
GROUND STATES
MATRIX ELEMENTS
MONTE CARLO METHOD
NUCLEI
QUANTUM NUMBERS
WAVE FUNCTIONS