Seminar Details

Advances in Coupled-Cluster Computations of Medium Mass and Neutron Rich Nuclei

Gaute Hagen, Oak Ridge National Laboratory (ORNL)
Tuesday, April 23, 11:00 AM - Theory Seminar
NSCL Seminar Room

In this talk I will present recent advances in computing properties of nuclei using coupled-cluster theory. The beauty of coupled-cluster theory is that it can naturally account for: (i) effects of three nucleon forces, (ii) the presence of open decay channels and particle continuum, and (iii) many-nucleon correlations. Advances in chiral effective field theory allow for a systematic derivation of many-nucleon forces and currents, and provide us with a systematic approach to quantify uncertainties in computed observables in nuclei. Recently we optimized the nucleon-nucleon interaction from chiral effective field theory at next‐to‐next‐to leading order (NNLO) using the mathematical optimization software POUNDerS (Practical Optimization Using No Derivatives for Squares), obtaining a χ2≈1 for laboratory energies below 125MeV [1]. We demonstrated with this optimized interaction, that several key aspects of nuclei can be understood without explicitly invoking three-nucleon forces. Other recent highlights include ab-initio coupled‐cluster calculation of the giant dipole resonance in 16O [2], coupled-cluster calculations of oxygen and calcium isotopes, with an emphasis on the evolution of shell structure. In particular we address the question regarding shell closure in 54Ca [3]. [1] “An optimized chiral nucleon‐nucleon interaction at next-to‐next‐to‐leading order”, A. Ekstrom, G. Baardsen, C. Forssen, G. Hagen, M. Hjorth-Jensen, G. R. Jansen, R. Machleidt, W. Nazarewicz, T. Papenbrock, J. Sarich, S. M. Wild, arXiv:1303.4674 (2013) [2] “First principles description of the giant dipole resonance in 16O”, Sonia Bacca, Nir Barnea, Gaute Hagen, Giuseppina Orlandini, Thomas Papenbrock, arXiv:1303.7446 (2013) [3] “Evolution of shell structure in neutron-rich calcium isotopes”, G. Hagen, M. Hjorth-Jensen, G. R. Jansen, R. Machleidt, T. Papenbrock, Phys. Rev. Lett. 109, 032502 (2012).