Merge pull request #4 from ml-evs/add-property-definitons-3

Add `space_group_symmetry_operations_xyz` and sub-definition for sym ops

schemas/src/defs/v1.2/properties/optimade/common/symmetry_operation_xyz.yaml

@@ -0,0 +1,22 @@
+$$schema: "https://schemas.optimade.org/meta/v1.2/optimade/property_definition"
+$id: "https://schemas.optimade.org/defs/v1.2/properties/optimade/common/symmetry_operation_xyz"
+title: "Symmetry operation"
+x-optimade-type: "string"
+x-optimade-definition:
+  label: "symmetry_operation_xyz_optimade_common"
+  kind: "property"
+  version: "1.2.0"
+  format: "1.2"
+  name: "symmetry_operation_xyz"
+description: |-
+  A symmetry operation given as general position x, y, z coordinates in algebraic form.
+
+  **Requirements/Conventions:**
+
+  - The symmetry operation is described by a string that gives that symmetry operation in Jones' faithful representation (Bradley & Cracknell, 1972: pp. 35-37), adapted for computer string notation.
+  - The letters `x`, `y` and `z` that are typesetted with overbars in printed text represent coordinate values multiplied by -1 and are encoded as `-x`, `-y` and `-z`, respectively.
+  - The syntax of the strings representing symmetry operations MUST conform to regular expressions given in appendix `The Symmetry Operation String Regular Expressions`_.
+x-optimade-unit: inapplicable
+type:
+  - "string"
+maxLength: 3

schemas/src/defs/v1.2/properties/optimade/structures/space_group_symmetry_operations_xyz.yaml

@@ -0,0 +1,42 @@
+$$schema: "https://schemas.optimade.org/meta/v1.2/optimade/property_definition"
+$id: "https://schemas.optimade.org/defs/v1.2/properties/optimade/structures/space_group_symmetry_operations_xyz"
+title: "Space group symmetry operations"
+x-optimade-type: "list"
+x-optimade-definition:
+  label: "space_group_symmetry_operations_xyz_optimade_structures"
+  kind: "property"
+  version: "1.2.0"
+  format: "1.2"
+  name: "space_group_symmetry_operations_xyz"
+type:
+  - "array"
+  - "null"
+description: |-
+  A list of symmetry operations given as general position x, y and z coordinates in algebraic form.
+
+  **Requirements/Conventions**:
+
+  - Each symmetry operation is described by a string that gives that symmetry operation in Jones' faithful representation (Bradley & Cracknell, 1972: pp. 35-37), adapted for computer string notation.
+  - The letters `x`, `y` and `z` that are typesetted with overbars in printed text represent coordinate values multiplied by -1 and are encoded as `-x`, `-y` and `-z`, respectively.
+  - The syntax of the strings representing symmetry operations MUST conform to regular expressions given in appendix `The Symmetry Operation String Regular Expressions`_.
+  - The interpretation of the strings MUST follow the conventions of the IUCr CIF core dictionary (IUCr, 2023).
+  - In particular, this property MUST explicitly provide all symmetry operations needed to generate all the atoms in the unit cell from the atoms in the asymmetric unit, for the setting used.
+  - This symmetry operation set MUST always include the `x,y,z` identity operation.
+  - The symmetry operations are to be applied to fractional atom coordinates.
+  - In case only Cartesian coordinates are available, these Cartesian coordinates must be converted to fractional coordinates before the application of the provided symmetry operations.
+  - If the symmetry operation list is present, it MUST be compatible with other space group specifications (e.g. the ITC space group number, the Hall symbol, the Hermann-Mauguin symbol) if these are present.
+
+  **Notes**:
+
+  - The list of space group symmetry operations applies to the whole periodic array of atoms and together with the lattice translations given in the :property:`lattice\_vectors` property provides the necessary information to reconstruct all atom site positions of the periodic material.
+  - Thus, the symmetry operations described in this property are only applicable to material models with at least one periodic dimension.
+  - This property is not meant to represent arbitrary symmetries of molecules, non-periodic (finite) collections of atoms or non-crystallographic symmetry.
+
+  **Bibliographic References**
+
+  - Bradley, C. J. and Cracknell, A. P. (1972) The Mathematical Theory of Symmetry in Solids. Oxford, Clarendon Press (paperback edition 2010) 745 p. ISBN `978-0-19-958258-7 <https://isbnsearch.org/isbn/9780199582587>`__.
+  - IUCr (2023) Core dictionary (coreCIF) version 2.4.5; data name `\_space\_group\_symop\_operation\_xyz`. Available from: https://www.iucr.org/__data/iucr/cifdic_html/1/cif_core.dic/Ispace_group_symop_operation_xyz.html [Accessed 2023-06-18T16:46+03:00].
+examples:
+  - ["x,y,z", "-x,y,-z"]
+  - ["x,y,z", "-x,y,-z", "x+1/2,y+1/2,z", "-x+1/2,y+1/2,-z"]
+x-optimade-unit: "unapplicable"