  We investigate via quantum molecular-dynamics simulations the thermophysical
properties of shocked liquid ammonia up to the pressure 1.3 TPa and temperature
120000 K. The principal Hugoniot is predicted from wide-range equation of
state, which agrees well with available experimental measurements up to 64 GPa.
Our systematic study of the structural properties demonstrates that liquid
ammonia undergoes a gradual phase transition along the Hugoniot. At about 4800
K, the system transforms into a metallic, complex mixture state consisting of
$\textnormal{N}\textnormal{H}_{3}$, $\textnormal{N}_{2}$, $\textnormal{H}_{2}$,
N, and H. Furthermore, we discuss the implications for the interiors of Uranus
and Neptune.
