"The proposed ice, which the researchers describe in a Feb. 12, 2016 study in the journal Science Advances, would be about 25 percent less dense than a record-low form synthesized by a European team in 2014.
If the ice can be synthesized, it would become the 18th known crystalline form of water—and the first discovered in the United States since before World War II. "We performed a lot of calculations (focused on) whether this is not just a low-density ice, but perhaps the lowest-density ice to date," said Xiao Cheng Zeng, an Ameritas University Professor of chemistry who co-authored the study. "A lot of people are interested in predicting a new ice structure beyond the state of the art."
This newest finding represents the latest in a long line of ice-related research from Zeng, who previously discovered a two-dimensional "Nebraska Ice" that contracts rather than expands when frozen under certain conditions.
Zeng's newest study, which was co-led by Dalian University of Technology's Jijun Zhao, used a computational algorithm and molecular simulation to determine the ranges of extreme pressure and temperature under which water would freeze into the predicted configuration. That configuration takes the form of a clathrate—essentially a series of water molecules that form an interlocking cage-like structure".