  Although the phase of water has extensively investigated whether there exists
a defect distorting only locally the structure still under debate. Here we
report a localized 5775 defect phase presented in the double layer ice on the
Au (111) surface, which is a metastable structure with 5- and 7-membered rings
compared with a perfect hexagonal one. Without altering the total number of the
hydrogen bonds of the ice, the defect only introduces 0.08 {\AA} molecular
displacement and 3.27% interaction energy change outside the defected area.
Such defect also exists without Au support but causes a larger lattice
relaxation or smaller interaction energy change. The excessively high barrier
as well as the low quantum tunneling and thermodynamic probabilities hinder the
formation of the defect by post-grown isomerization from the perfect to the
defected structure. This finding indicates that the defected ice is stable, and
the defect can be formed during the ice growth stage.
