Exercises

API usage and data processing - Python

For the material Al₂O₃ with space group 167 are various calculations with DOS data available.

• Find the material ID
• Get the data from all calculations with DOS
• Print all the DOS diagrams such that one can compare them.

3D viewer extension - Javascript

The following code provides some routines for accessing the API and preparing the crystal structure data for the 3D viewer.

• Extend index.html such that it shows the structure for any material given by material ID

  function apiReq(materialId, dataType, authToken, callback){
    let oReq = new XMLHttpRequest();
    oReq.addEventListener("load", callback);
    oReq.open("GET", "https://encyclopedia-api.nomad-coe.eu/v1.0/materials/"+materialId+"/"+dataType);
    oReq.setRequestHeader('Authorization', 'Basic '+btoa(authToken));
    oReq.send();
    return oReq;
  }
  
  
  function getMaterialStructureDataFromAPI(materialId, authToken, callback){
  
    apiReq(materialId, 'elements', authToken, e => {
            let elements = JSON.parse(e.target.response).results;
  
            apiReq(materialId, 'cells', authToken, e1 => {
                    let cells = JSON.parse(e1.target.response).results;
                    let cell;
                    if (!cells[0].is_primitive) cell= cells[0];
                    else cell= cells[1];
  
                    callback(getCellDataForViewer(elements, cell));
            });
    });
  }
  
  
  function getNumberArray(string){
    let sArray= string.substring(1,string.length-1).split(',');
    let fArray= [];
    for (let i = 0; i < sArray.length; i++) {
      fArray.push(parseFloat(sArray[i]));
    }
    return fArray;
  }
  
  
  function getCellDataForViewer(elements, cell){
    let cellData= {};
    cellData.normalizedCell= [
      getNumberArray(cell.a),
      getNumberArray(cell.b),
      getNumberArray(cell.c)
    ];
  
    cellData.labels= [];
    cellData.positions= [];
  
    for (let i = 0; i < elements.length; i++) {
      cellData.labels.push(elements[i].label);
      cellData.positions.push(getNumberArray(elements[i].position));
    }
  
    //cellData.periodicity = JSON.parse(matData.periodicity);
  
    return cellData;
  }