diff --git a/cif_core.dic b/cif_core.dic index d648d17..154d62c 100644 --- a/cif_core.dic +++ b/cif_core.dic @@ -11,7 +11,7 @@ data_CIF_CORE _dictionary.title CIF_CORE _dictionary.class Instance _dictionary.version 3.4.0 - _dictionary.date 2026-06-23 + _dictionary.date 2026-07-10 _dictionary.uri https://raw.githubusercontent.com/COMCIFS/cif_core/main/cif_core.dic _dictionary.ddl_conformance 4.2.0 @@ -12476,6 +12476,172 @@ save_space_group.point_group_h-m save_ +save_space_group.reference_setting + + _definition.id '_space_group.reference_setting' + _definition.update 2026-07-10 + _description.text +; + The reference setting of a given space group is the setting + chosen by the International Union of Crystallography as a + unique setting to which other settings can be referred + using the transformation matrix column pair given in + _space_group.transform_Pp_abc and _space_group.transform_Qq_xyz. + + The settings are given in the enumeration list in the form + '_space_group.IT_number:_space_group.name_Hall'. The + space-group number defines the space-group type and the + Hall symbol specifies the symmetry generators referred to + the reference coordinate system. + + The 230 reference settings chosen are identical to the settings + listed in International Tables for Crystallography Volume A + (2002). For the space groups where more than one setting is + given in International Tables, the following choices have + been made. + + For monoclinic space groups: unique axis b and cell choice 1. + + For space groups with two origins: origin choice 2 (origin at + inversion centre, indicated by adding :2 to the Hermann-Mauguin + symbol in the enumeration list). + + For rhombohedral space groups: hexagonal axes (indicated by + adding :h to the Hermann-Mauguin symbol in the enumeration list). + + Based on the symmetry table of R. W. Grosse-Kunstleve, ETH, + Zurich. + + In the enumeration list, each reference setting is identified + by Schoenflies symbol and by the Hermann-Mauguin symbol, + augmented by :2 or :h suffixes as described above. + + Ref: International Tables for Crystallography (2002). Volume A, + Space-group symmetry, edited by Th. Hahn, 5th ed. + Dordrecht: Kluwer Academic Publishers. + + Grosse-Kunstleve, R. W. (2001). Xtal System of + Crystallographic Programs, System Documentation. + https://xtal.sourceforge.net/man/symmetry.html + (or follow links to Documentation->Xtal Users Manual->Symmetry from + https://xtal.sourceforge.net). +; + _name.category_id space_group + _name.object_id reference_setting + _type.purpose State + _type.source Assigned + _type.container Single + _type.contents Text + + _import.get [{'file':templ_enum.cif 'save':ref_set}] + +save_ + +save_space_group.transform_pp_abc + + _definition.id '_space_group.transform_Pp_abc' + _definition.update 2026-07-10 + _description.text +; + This item specifies the transformation (P,p) of the basis + vectors from the setting used in the CIF (a,b,c) to the + reference setting given in _space_group.reference_setting + (a',b',c'). The value is given in Jones faithful notation + corresponding to the rotational matrix P combined with the + origin shift vector p in the expression: + + (a',b',c') = (a,b,c)P + p. + + P is a post-multiplication matrix of a row (a,b,c) of column + vectors. It is related to the inverse transformation (Q,q) by: + + P = Q^-1^ + p = Pq = -(Q^-1^)q. + + These transformations are applied as follows: + + atomic coordinates (x',y',z') = Q(x,y,z) + q + Miller indices (h',k',l') = (h,k,l)P + symmetry operations W' = (Q,q)W(P,p) + basis vectors (a',b',c') = (a,b,c)P + p + + This item is given as a character string involving the + characters a, b and c with commas separating the expressions + for the a', b' and c' vectors. The numeric values may be + given as integers, fractions or real numbers. Multiplication + is implicit, division must be explicit. White space within + the string is optional. +; + _name.category_id space_group + _name.object_id transform_Pp_abc + _type.purpose Encode + _type.source Recorded + _type.container Single + _type.contents Text + + loop_ + _description_example.case + _description_example.detail + '-b+c, a+c, -a+b+c' 'R3:r to R3:h' + 'a-1/4, b-1/4, c-1/4' 'Pnnn:1 to Pnnn:2' + 'b-1/2, c-1/2, a-1/2' 'Bbab:1 to Ccca:2' + +save_ + +save_space_group.transform_qq_xyz + + _definition.id '_space_group.transform_Qq_xyz' + _definition.update 2026-07-10 + _description.text +; + This item specifies the transformation (Q,q) of the atomic + coordinates from the setting used in the CIF [(x,y,z) referred + to the basis vectors (a,b,c)] to the reference setting given in + _space_group.reference_setting [(x',y',z') referred to the + basis vectors (a',b',c')]. + + The value given in Jones faithful notation corresponds to the + rotational matrix Q combined with the origin shift vector q in + the expression: + + (x',y',z') = Q(x,y,z) + q. + + Q is a pre-multiplication matrix of the column vector (x,y,z). + It is related to the inverse transformation (P,p) by: + + P = Q^-1^ + p = Pq = -(Q^-1^)q, + + where the P and Q transformations are applied as follows: + + atomic coordinates (x',y',z') = Q(x,y,z) + q + Miller indices (h',k',l') = (h,k,l)P + symmetry operations W' = (Q,q)W(P,p) + basis vectors (a',b',c') = (a,b,c)P + p + + This item is given as a character string involving the + characters x, y and z with commas separating the expressions + for the x', y' and z' components. The numeric values may be + given as integers, fractions or real numbers. Multiplication + is implicit, division must be explicit. White space within + the string is optional. +; + _name.category_id space_group + _name.object_id transform_Qq_xyz + _type.purpose Encode + _type.source Recorded + _type.container Single + _type.contents Text + + loop_ + _description_example.case + _description_example.detail + '-x/3+2y/3-z/3, -2x/3+y/3+z/3, x/3+y/3+z/3' 'R3:r to R3:h' + 'x+1/4, y+1/4, z+1/4' 'Pnnn:1 to Pnnn:2' + 'z+1/2, x+1/2, y+1/2' 'Bbab:1 to Ccca:2' + +save_ + save_symmetry.cell_setting _definition.id '_symmetry.cell_setting' @@ -29275,7 +29441,7 @@ save_ _atom_site.U_iso_or_equiv. [bm, after Nespolo, M. (2024). J. Appl. Cryst. 57, 1733-1746] ; - 3.4.0 2026-06-23 + 3.4.0 2026-07-10 ; # Append change information below and update the above date # until dictionary is ready for release. @@ -29299,4 +29465,7 @@ save_ Changed the _diffrn_source.device data item enumeration value from 'rot_anode' to 'rot-anode'. + + Added _space_group.reference_setting, _space_group.transform_Pp_abc, and + _space_group.transform_Qq_xyz from symCIF to SPACE_GROUP. ;