Quantum-mechanical exploration of the phase diagram of water

摘要: The phase diagram of water harbours many mysteries: some the boundaries are fuzzy, and set known stable phases may not be complete. Starting from liquid a comprehensive 50 ice structures, we compute at three hybrid density-functional-theory levels approximation, accounting for thermal nuclear fluctuations as well proton disorder. Such calculations only made tractable because combine machine-learning methods advanced free-energy techniques. computed is in qualitative agreement with experiment, particularly pressures $\lesssim$8000 bar, discrepancy chemical potential comparable subtle uncertainties introduced by disorder spread between functionals. None hypothetical considered thermodynamically our calculations, suggesting completeness experimental region considered. Our work demonstrates feasibility predicting polymorphic system first principles provides thermodynamic way testing limits quantum-mechanical calculations.