James Brownridge, a physicist at Binghamton University, has said that supercooling is involved. Several molecular dynamics simulations have also supported that changes in hydrogen bonding during supercooling take a major role in the process. In 2017, Yunwen Tao and co-authors suggested that the vast diversity and peculiar occurrence of different hydrogen bonds could contribute to the effect. They argued that the number of strong hydrogen bonds increases as temperature is elevated, and that the existence of the small strongly bonded clusters facilitates in turn the nucleation of hexagonal ice when warm water is rapidly cooled down. The authors used vibrational spectroscopy and modelling with density functional theory -optimized water clusters.