Porous ices with ultralow-density assembled from water polyhedral cages and ice nanotubes

Porous ice represents an emerging class of crystalline ice phases characterized by extensive nano-cavities and/or nano-channels within their hydrogen-bonded water frameworks. The prediction of ultralow-density porous ices is of particular interest, as their high surface-to-volume ratio could significantly expand their practical applications. In this work, we assembled two series of ultralow-density porous ices from polyhedral water cages and ice nanotubes, designated as SOD_n and LTA_n, respecti