Three-dimensional calculation of inhomogeneous structure in low-density nuclear matter

Okamoto, Minoru; Maruyama, Toshiki  ; Tatsumi, Toshitaka*; Yabana, Kazuhiro*

In low-density nuclear matter, non-uniform structures called "nuclear pasta" are expected. So far, most works on nuclear pasta have used the Wigner-Seitz (WS) cell approximation with geometrical symmetry, which reduces the calculation into one-dimensional space. However, this approximation brings about limitation of the structure within typical pasta structures. On the other hand, some works report possibilities of more complicated structures such as gyroid, double-diamond, etc. In this context we perform fully three-dimensional calculations of nuclear matter based on the relativistic mean-field model and the Thomas-Fermi approximation. We demonstrate that pasta structures, previously given by the WS cell approximation, also appear in the three-dimensional calculation. The most stable structure of matter with and without WS cell approximation are compared. We also present newly observed structures which may appear as exited states of matter.