Comparison of Structures of Solid Alums Predicted using PM7 with X-Ray

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HoF Errors: < 2 kcal/mol   < 5 kcal/mol   < 10 kcal/mol   < 20 kcal/mol   < 50 kcal/mol.   Geometries: 0: good, 100: bad

     #     GUI  Heat of formation (Kcal/formula unit)  Geometry        Species
                   Ref.        PM7        PM6        PM7    PM6 
     1   (JSmol)             -1495.0    -1253.4       14.2   26.5  Ammonium aluminum sulfate ((NH4)Al(SO4)2 (12(H2O))
     2   (JSmol)             -1466.5    -1245.3       15.9   25.7  Sodium alum (NaAl(SO4)2 12(H2O))
     3   (JSmol)             -1464.4    -1250.5       20.4   43.4  Potassium alum (KAl(SO4)2 12(H2O))
     4   (JSmol)             -1236.9    -1172.0       32.0   35.1  Ammonium chromium(III) alum ((NH4)Cr(SO4)2 12(H2O))
     5   (JSmol)             -1186.4    -1017.5       31.8   54.1  Chromium potassium alum (KCr(SO4)2 12(H2O))
     6   (JSmol)             -1198.1    -1186.9       19.9   23.1  Rubidium chromium alum (RbCr(III)(SO4)2 12(H2O))
     7   (JSmol)             -1301.7     -970.8       14.7   48.3  Cesium iron(iii) sulfate dodecahydrate (CsFe(SO4)2 (H2O)12) (ICSD 201213)