We derive coupled-cluster equations for three-body Hamiltonians. The equations for the one- and two-body cluster amplitudes are presented in a factorized form that leads to an efficient numerical implementation. We employ low-momentum two- and three-nucleon interactions and calculate the binding energy of 4He. The results show that the main contribution of the three-nucleon interaction stems from its density-dependent zero-, one-, and two-body terms that result from the normal ordering of the Hamiltonian in coupled-cluster theory. The residual three-body terms that remain after normal ordering can be neglected.

%B Physical Review C %V 76 %P 11 pages %8 09/2007 %G eng %N 3 %0 Journal Article %J International Journal of Modern Physics B %D 2006 %T Coupled Cluster Theory for Nuclei %A T. Papenbrock %A D. J. Dean %A J. R Gour %A G. Hagen %A M. {Hjorth-Jensen} %A M. Wloch %K Nuclear structure; light nuclei; coupled-cluster theory %XThis presentation focuses on some of the recent developments in low-energy nuclear structure theory, with emphasis on applications of coupled-cluster theory. We report on results for ground and excited states in 4He and 16O, and about extensions of coupled-cluster theory to treat three-body forces.

%B International Journal of Modern Physics B %V 20 %P 5338-5345 %G eng %N 30-31 %0 Journal Article %J Nuclear Physics A %D 2005 %T Nuclear Structure Calculations with Coupled-Cluster Methods from Quantum Chemistry %A Piotr Piecuch %A D. J. Dean %A J. R Gour %A G. Hagen %A M. {Hjorth-Jensen} %A K. Kowalski %A T. Papenbrock %A M. Wloch %XWe present several coupled-cluster calculations of ground and excited states of 4He and 16O employing methods from quantum chemistry. A comparison of coupled cluster results with the results of exact diagonalization of the hamiltonian in the same model space and other truncated shell-model calculations shows that the quantum chemistry inspired coupled cluster approximations provide an excellent description of ground and excited states of nuclei, with much less computational effort than traditional large-scale shell-model approaches. Unless truncations are made, for nuclei like 16O, full-fledged shell-model calculations with four or more major shells are not possible. However, these and even larger systems can be studied with the coupled cluster methods due to the polynomial rather than factorial scaling inherent in standard shell-model studies. This makes the coupled cluster approaches, developed in quantum chemistry, viable methods for describing weakly bound systems of interest for future nuclear facilities.

%B Nuclear Physics A %V 752 %P 299-308 %8 04/2005 %G eng