  Heterogeneous ice nucleation is one of the most common and important process
in the physical environment. AgI has been proved to be an effective ice
nucleating agent in the process of ice nucleation. However, the microscopic
mechanism of AgI in heterogeneous ice nucleation has not been fully understood.
Molecular dynamics simulations are applied to investigate the ability of which
kinds of $\gamma$-AgI substrate can promote ice nucleation by changing the
dipole of $\gamma$-AgI on the substrate, we conclude that the dipole of
$\gamma$-AgI on the substrate can affect the conformation of ice nucleation.
The surface ions with positive charge on the substrate may promote ice
nucleation, while there is no ice nucleation founded on the surface ions with
negative charge. $\gamma$-AgI substrates affect ice nucleation through adjust
the orientations of water molecules near the surfaces.
