Theoretical study of density condition of solid metallic hydrogen for fuel pellet

Hydrogen fuel pellet is often used in the laser fusion. In many cases, the hydrogen state as a fuel pellet is kept in low temperature in order to achieve high density solid or liquid states. Such states are very delicate and not easy to handle. On the other hand, a solid metallic state is said to possess similar high density. Additionally, it could be metastable in ambient temperature and utilized as a maintenance free fuel pellet. We have focused on the solid atomic hydrogen and studied theoretically the density condition of the metallization. In this study, we have picked up seven crystalline structures and compared the transition density for each structure. It is found that the density becomes higher as its structural filling factor becomes larger.