Computational investigation into the phase transitions from AlPO₄-H₃

Molecular dynamics simulation approach has been used to investigate the phase transitions from aluminophosphate AlPO₄-H₃. Derived from AlPO₄-H₃, several hypothetical models of its high-temperature phases are designed through removing the bridged water molecules and changing the up-down connected sequences of T-sites in the 4-membered rings. Full geometry optimizations is performed to obtain structural parameters for the models that are compared to the reported data, and their structure features and thermodynamic stabilities have been discussed. The simulation study suggests that AlPO₄-H₃ is energetically favored to transform to AlPO₄-C, and then to AlPO₄-D as well as to other novel hypothetical 3D open-frameworks.