Coupled-Cluster Theory for Nuclear Structure

• Main Author: Binder, Sven
• Format: Others
• Language: English; en
• Published: 2014
• Online Access: https://tuprints.ulb.tu-darmstadt.de/3946/1/Thesis%20-%20Binder.pdf; Binder, Sven <http://tuprints.ulb.tu-darmstadt.de/view/person/Binder=3ASven=3A=3A.html> (2014): Coupled-Cluster Theory for Nuclear Structure.Darmstadt, Technische Universität, [Ph.D. Thesis]

Nuclear Hamiltonians constructed within chiral effective field theory provide an unprecedented opportunity to access nuclear phenomena based on low-energy quantum chromodynamics and, in combination with sophisticated many-body methods, allow for an ab initio description of nuclei without resorting to phenomenology. This work focuses on the inclusion of chiral two-, and in particular three-body Hamiltonians into many-body calculations, with emphasis on the formal and computational aspects related to the three-body interactions. Through similarity renormalization group evolutions, the chiral Hamiltonians are transformed into a form in which strong short-range correlations are tamed in order to accelerate the convergence in the subsequent many-body calculations. The many-body method mainly used is an angular-momentum coupled formulation of coupled-cluster theory with an iterative treatment of singly and doubly excited clusters, and two different approaches to non-iteratively include effects of triply excited clusters. Excited nuclear states are accessed via the equation-of- motion coupled-cluster framework. The extension of coupled-cluster theory to three-body Hamiltonians is considered to verify the approximate treatment of three-nucleon interactions via the normal-ordering two-body approximation as a highly efficient and accurate way to include three-nucleon interactions into the many-body calculations, particularly for heavier nuclei. Using a single chiral Hamiltonian whose low-energy constants are fitted to three- and four-body systems, a qualitative reproduction of the experimental trend of nuclear binding energies, from 16O up to 132Sn, is achieved, which hints at the predictive power of chiral Hamiltonians, even in the early state of development they are at today.