Abstract: The lattice energy of a series of aluminophosphate molecalar sieves was deter-mined by using the lattice energy minimization method.The results were compared to thelattice energy of dense polymorphs of AlPO₄. All AlPO₄ molecular sieves frameworks are on-ly 48-127 kJ/mol less stable than berlinite.This may explain the structural diversity andsimilarity observed for aluminophosphate molecular sieves.These XRDdata of the AlPO₄molecular sieves contain a very short Al-Obond length(0.1478 nm) and P-Obond length(0.1348 nm), very long Al-Obond length (0.1942 nm)and P-Obond length (0.1678nm), and a large range of O-Al-Oangles(98.62°-122.27°) and O-P-Oangles (92.36°-122.86°), an averge Al-O-Pangle is closes to 153° and a larger range of Al-O-Pan-gles (114.80°-180°).AM1 molecular Orbital calculation have shown that there is a smallbarrier (22.97 kJ/mol) to variation in the Al-O-Pangle between 114°and 180°, and thereis the lowest energy for angles 137.74°.

Key words: Aluminophosphate molecular sieves, Lattice energy minimization, Bond length-es, Bond angles, Structure and property