key indicators in Crystallographic Communications
Each article published in Structure Reports Online includes a set of key indicators, giving a summary of the main descriptors of the precision and completeness of the study, with indications of problems such as disorder.
The following table describes the key indicators that may be included with an article, and gives the conditions under which each one is included.
Indicator | Description | Source | Example as displayed in an article | Interpretation of example |
Study type | This indicator consists of two parts, the method and the source used for the study. | Derived from the CIF. | Single-crystal X-ray study | Single-crystal X-ray study |
Conditions (temperature and pressure) | This indicator consists of two parts, the temperature (in K) and the pressure (in kPa) at which the study was performed. The pressure is only recorded if it is not ambient pressure. | Direct from the CIF. | T = 297 K | Temperature 297 K. Ambient pressure. |
T = 297 K, P = 120 kPa | Temperature 297 K. Pressure 120 kPa. | |||
Geometry precision | Mean (C-C) (in Å), to three decimal places. In the case of no C-C bonds being present this is the mean between the two lightest atom species (but not lighter than C). | Determined by the PLATON program. | Mean (C-C) = 0.002 Å | Mean (C-C) = 0.002 Å |
Completeness | Non-H-atom completeness is recorded as true or false. H-atom completeness is recorded as a percentage value. A value of less than 100 is only included in the article if non-H atoms are all present. | Determined by comparison of the sum formula and the _atom_site data provided in the CIF. | The structure is complete. | |
Some non-H atoms missing | Some non-H atoms are missing. There may or may not also be some H atoms missing. | |||
H-atom completeness 90% | H atoms are 90% complete but all non-H atoms are present. | |||
Disorder | Disorder in main residue or disorder in solvent or counterion may be included. | Determined by the PLATON program. | There is no disorder in the main residue or in the solvent or counterion. | |
Disorder in solvent or counterion | There is disorder in the solvent or counterion, but no disorder in the main residue. | |||
Disorder in main residue | There is disorder in the main residue. There may or may not also be disorder in the solvent or counterion. | |||
R factor | This is the R factor presented in the article (to three decimal places). | Direct from the CIF. | R factor = 0.045 | R factor = 0.045 |
wR factor | This is the wR factor presented in the article (to three decimal places). | Direct from the CIF. | wR factor = 0.135 | wR factor = 0.135 |
Data-to-parameter ratio | The data-to-parameter ratio is calculated to one decimal place. | Directly determined from the CIF. | Data-to-parameter ratio = 18.5 | Data-to-parameter ratio = 18.5 |