The energetics of different ordering schemes for NaAlSi3O8 (albite) were investigated by both empirical potential and ab initio methods. These computations indicate that the ordered structure of natural low albite, in which aluminum atoms reside on the T10 site, is favored by 30 meV (2.9 kJ/mol) over the corresponding structure in which aluminum atoms are ordered onto the T20 site. Permissible lattice relaxation of the T10 structure, with an associated substantial decrease in the γ lattice angle, is unique to the T10 structure and appears to be responsible for its substantially lower enthalpy.

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