Relativistic density functional theory in nuclear physics

The development of rare isotope beam facilities worldwide has extended our knowledge of nuclear physics from stable nuclei to unstable nuclei. The description of properties emerged from these unstable nuclei is one of the major goals for the nuclear community. However, it is known that the nuclear many-body problem is rather difficult to solve, especially for heavy nuclei. To have a comprehensive understanding of nuclear systems, one should in principle solve the nuclear many-body problem in a fully microscopic way. Over the past decades, nuclear density functional theories have been greatly developed and successfully applied to describe and explain many nuclear phenomena. In particular, the relativistic density functional theory based on the relativistic quantum field theory and the density functional theory has received wide attention due to its attractive advantages. In the nuclear relativistic density functional theory, nucleons are described by Dirac spinors and the Lorentz symmetry is considered in constructing the nucleonic densities and currents. As a result, the spin degrees of freedom for nucleons are automatically taken into account and the pseudospin symmetry could be naturally explained. In addition, due to the consideration of Lorentz symmetry, the nuclear currents induced by the spatial parts of nuclear vector self-energies are included naturally, which have been proven to be very important for the description of nuclear excitations. In this paper, we briefly introduce the basic concepts and ideas of the nuclear relativistic density functional theory and emphasize its advantages in the description of nuclear properties for the ground states and excited ones. After a short review on its historical development, the recent applications of the relativistic density functional theory to nuclear masses, nuclear chiral precession, and nuclear fission dynamics based on the well-known PC-PK1 relativistic density functional are illustrated. By taking into account the triaxial degree of freedom and the dynamical correlation energy, which is given by a five-dimensional collective Hamiltonian based on the microscopic relativistic density functional, the masses for all even-even nuclei have been discussed. In comparison with the data available, the calculated results well reproduce the data globally with an accuracy of about 1 MeV. The relativistic density functional theory has recently been extended to the time-dependent case in three-dimensional lattice space, and successfully applied to nuclear scattering, fusion, chirality, and fission. In this paper, the chiral precession in rotating triaxial nuclei is particularly discussed. Moreover, the study of nuclear fission dynamics based on the time-dependent relativistic density functional theory has also been discussed, where the formation of a clusters in the fission neck is mainly emphasized. The recent results given by relativistic ab initio calculations including those from the relativistic Brueckner-Hartree-Fock theory and those based on the leading-order covariant pionless chiral effective theory are also briefly mentioned. These pieces of work have laid a foundation for an ab initio nuclear relativistic density functional theory, and together with the rapidly growing large-scale super computers, we believe that there will be more exciting work in the near future.

Automated summary

The development of rare isotope beam facilities has expanded our knowledge of nuclear physics and solving the nuclear many-body problem is a crucial task. The relativistic density functional theory has been widely studied and applied in the description of nuclear properties. This paper provides an introduction to the theory and highlights its advantages in describing nuclear properties.