Oak Ridge National Laboratory

Physics Division

Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,

Alfredo Galindo-Uribarri
Tel (Office): (865) 574-6124  (FAX): (865) 574-1268

Thu., December 04, 2003, at 3:00 p.m.

Challenges of the nuclear quantum many-body problem

David Dean, ORNL Physics Division
Bldg. 6008 Conference Room

One of the frontiers we face in nuclear science today is the discovery, description, and understanding of exotic nuclei. Aside from their intrinsic interest, these nuclei play an important role in element production in the universe. These unstable neutron-rich nuclei offer a number of challenges: they will often be far from closed core configurations, and are often weakly bound. They will therefore be difficult to describe with conventional theoretical methods. Experimental techniques and the promise of major future facilities like the Rare Isotope Accelerator (RIA) in the US, the GSI upgrade in Germany, the ISAC-II facility in Canada, and the RIKEN accelerator in Japan, are indeed pushing us into new regions of the nuclear many-body problem. Thus various ab initio methods must be pursued that will allow for a theoretical description of the nuclear many-body problem for both stable and unstable systems. These methods often require significant amounts of computational power for their implementation.

In this colloquium, I will begin by surveying some of the exciting and open challenges that facilities like RIA will present nuclear theory. I will then discuss the application of coupled cluster theory to the nuclear many-body problem. Surprisingly few applications of coupled cluster theory have been pursued in nuclear physics since initial investigations by Zabolitsky, et al., in the early 1970's and the original description of the theory by Coester in the late 1950's. While the nuclear physics community did not pursue these approaches beyond the early initial studies (and some recent work by Heisenberg, et al.) they were pursued with vigor in computational quantum chemistry and have become the method of choice for precise calculations of both ground and excited state properties of both atoms and molecules, and for chemical reaction studies.

Coupled cluster methods have been applied in chemistry up to the four- and five-cluster levels. As a first step of application in modern nuclear many-body problem, I will apply these methods at the one- and two-cluster (single and double correlations) level, and also discuss three-cluster corrections. Instead of directly applying this technique to the bare nucleon-nucleon interaction, I will use instead a renormalized two-body interaction as the starting point. During the talk, I will assess the applicability of the overall approach to the nuclear many-body problem.