Covariant density functional theory for nuclear fission based on a two-center harmonic oscillator basis

Background: Nowadays, modern microscopic approaches for fission are generally based on the framework of nuclear density functional theory (DFT), which has enabled a self-consistent treatment of both static and dynamic aspects of fission. The key issue is a DFT solver with high precision and efficiency especially for the large elongated configurations. Purpose: We aim to develop a DFT solver with high precision and efficiency based on the point coupling covariant density functional theory (CDFT), which has achieved great success in describing properties of nuclei for the whole nuclear chart. Method: We have extended the point-coupling CDFT to be based on the two-center harmonic oscillator (TCHO) basis, which matches well with the large elongated configurations during the fission process. A multidimensional constraint and the time-dependent generator coordinate method (TDGCM) have been used to analyze the fission potential energy surface (PES) and fission dynamics, respectively. To simulate the splitting process of the nascent fragments beyond scission, we also introduce a density constraint into the new CDFT framework. Results: Illustrative calculations have been done for the PESs and induced fission dynamics of two typical examples: ^226Th and ^240Pu. A more reasonable PES is obtained in the new framework compared to that based on the one-center harmonic oscillator (OCHO) with the same basis space. An optimization of about 0. 2--0. 3 MeV has been achieved for the outer fission barriers and large elongated configurations. The dynamical simulations based on CDFT-TCHO show an improved description of fission yields. Conclusions: The newly developed CDFT solver optimizes the elongated configurations, improves the calculation efficiency, and provides a basis for large-scale multidimensional constraint calculations and dynamical simulations.