Update README.md

citing to Optimade, adding MP links for spaces

README.md

@@ -287,7 +287,7 @@ df = dataset['train'].to_pandas()
 
 ## Data fields
 
-| **Feature name** | **Data type** | **Description** | **Optimade required field** |
+| **Feature name** | **Data type** | **Description** | **[Optimade](https://www.optimade.org/optimade) required field** |
 | --- | --- | --- | --- |
 | **elements** | Sequence[String] | A list of elements in the structure. For example a structure with composition Li2O7 will have `[”Li”,”O”]` in its elements.  Notes: Currently not necessarily sorted but future iteration will be sorted by alphabetic order. | ✅ |
 | **nsites** | Integer | The total number of sites in the structure. For example a structure with an un-reduced composition of Li4O2 will have a total of `6` sites. | ✅ |
@@ -300,7 +300,7 @@ df = dataset['train'].to_pandas()
 | **lattice_vectors** | Sequence[Sequence[Floats]], shape = 3x3 | The matrix of the structures. For example a cubic system with a lattice a=4.5 will have a `[[4.5,0,0],[0,4.5,0],[0,0,4.5]]` lattice vector entry. | ✅ |
 | **immutable_id** | String | The material ID associated with the structure from the respective database. Note: OQMD IDs are simply integers, thus we converted them to be “oqmd-YYY” | ✅ |
 | **cartesian_site_positions** | Sequence[Sequence[Floats]], shape = Nx3 | In cartesian units (not fractional units) the coordinates of the species. These match the ordering of all site based properties such as `species_at_sites`, `magneitc_moments` and `forces`. For example a material with a single element placed at a fractional coordinate of [0.5, 0.5, 0.5] with a cubic lattice with a=2, will have a cartesian_site_positions of `[1, 1, 1]`. | ✅ |
-| **species** | JSON | An optimade field that includes information about the species themselves, such as their mass, their name, their labels, etc. Note: we have not currently filled out the mass portion of the species. Additionally, none of our inputted structures should be solid solution thus the on-site concentration for all our species should be [1]. This is an Optimade field. | ✅ |
+| **species** | JSON | An [Optimade](https://www.optimade.org/optimade) field that includes information about the species themselves, such as their mass, their name, their labels, etc. Note: we have not currently filled out the mass portion of the species. Additionally, none of our inputted structures should be solid solution thus the on-site concentration for all our species should be [1]. This is an Optimade field. | ✅ |
 | **species_at_sites** | Sequence[String] | An array of the chemical elements belonging to each site, for example a structure with an un-reduced composition of Li2O2 may have an entry of `[”Li”, “Li”, “O”, “O”]` for this field, where each species should match the other site based properties such as `cartesian_site_positions`. | ✅ |
 | **last_modified** | Date/time | The date that the entry was last modified from the respective database it was pulled from. Note: we could not find this information in OQMD so we used the date of the latest database release as the input for this field. | ✅ |
 | **elements_ratios** | Dictionary | The fractional composition for a given structure in dictionary format. For example a structure with an unreduced composition of Li2O4 would have an entry of `{’Li’:0.3333, ‘O’:0.6667}` | ✅ |
@@ -386,8 +386,8 @@ Any structure which has a duplicate based on this method is dropped, only keepin
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-                <td>Let's you browse entries in our database, view the crystal structure and its associated properties.</td>
-                <td>Lets you generate binary and ternary phase diagram using various correction scheme.<br><br><u>Disclaimer</u>: the MP2020 correction scheme has not yet been uniformed across datasets, when using this correction scheme please be cautious about interpreting data. We will fix this in upcoming release!</td>
+                <td>Let's you browse entries in our database, view the crystal structure and its associated properties. Built using <a target="_blank" rel="noopener noreferrer" href="https://github.com/materialsproject/dash-mp-components">Materials Project's dash components</a></td>
+                <td>Lets you generate binary and ternary phase diagram using various correction scheme. Built using the Phase Diagram <a target="_blank" rel="noopener noreferrer" href="https://github.com/materialsproject/crystaltoolkit">Crystal Toolkit</a> component by the Materials Project<br><br><u>Disclaimer</u>: the MP2020 correction scheme has not yet been uniformed across datasets, when using this correction scheme please be cautious about interpreting data. We will fix this in upcoming release!</td>
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@@ -438,6 +438,8 @@ If you use materials data which include (”agm-”) in the immutable_id, please
 
 If you use materials data which include (”oqmd-”) in the immutable_id, please cite [OQMD](https://link.springer.com/article/10.1007/s11837-013-0755-4). 
 
+If you make use of Optimade in your research, please cite [Optimade](https://doi.org/10.1038/s41597-021-00974-z)
+
 Finally, if you make use of the Phase Diagram for visualization purposes, or the crystal viewer in the Materials Explorer, please acknowledge [Crystal Toolkit](https://github.com/materialsproject/crystaltoolkit).
 
 ## License