부산대학교 도서관

We develop a method based on equation-of-motion coupled-cluster theory to describe properties of open-shell nuclei with A±2 nucleons outside a closed shell. We perform proof-of-principle calculations for the ground states of the helium isotopes 3-6He and the first excited 2+ state in 6He. The comparison with exact results from matrix diagonalization in small model spaces demonstrates the accuracy of the coupled-cluster methods. Three-particle-one-hole excitations of 4He play an important role for the accurate description of 6He. For the open-shell nucleus 6He, the computational cost of the method is comparable with the coupled-cluster singles-and-doubles approximation while its accuracy is similar to the coupled-cluster with singles, doubles, and triples excitations. [ABSTRACT FROM AUTHOR]