Molecular dynamics for dense matter

Maruyama, Toshiki  ; Watanabe, Gentaro*; Chiba, Satoshi

We review our works on the molecular dynamics studies on the structures and dynamics of nuclear matter relevant to the neutron star crusts and supernova cores. First we focus on the "pasta" structures of low-density nuclear matter which have been predicted by many works with assuming the nuclear shape. In our works by the use of quantum molecular dynamics, we do not need assume any geometry. Next we show our calculation with a compression of the system which corresponds to the collapsing stage of supernova. With the increase of density, a crystalline solid of spherical nuclei will change to a triangular lattice of rods by connection of two neighboring nuclei. Finally, we discuss the fragment formation of expanding nuclear matter. Unlike a generally accepted scenario based on the gas-liquid phase transition, cold solid like matter breaks into fragments by the formation of cracks.