  Ab initio molecular dynamic method within the framework of density functional
theory is applied to analyze the structural and electronic properties of
crystalline molecular hydrogen at temperature 100\,K. Pressure, pair
correlation function and band structure are calculated. The crossover of
molecular crystalline hydrogen from the state of a semiconductor to a
semimetallic and metallic state is observed upon compression in the pressure
range of 302-626\,GPa. At pressures below 361\,GPa, the molecular crystal with
the C2/c structure is a semiconductor with an indirect gap. In the pressure
range 361 - 527\,GPa, band structure of the monoclinic C2/c lattice has a
characteristic semimetalic profile with partially unoccupied valence band and
partially occupied conduction band. When compressed to pressures above
544\,GPa, the structure changes from monoclinic C2/c to orthorhombic Cmca,
accompanied by a sharp decrease (by more than two orders of magnitude) in the
value of the direct gap, which is an indication of the metallic conductivity of
the resulting structure. The metallic state is metastable and exists up to a
pressure of 626\,GPa.
