code: private double getCovalentRadius(String symbol, IBond.Order maxBondOrder) {
          double radiusTarget = 0;
          if (symbol.equals("F")) {
              radiusTarget = 0.64;
          } else if (symbol.equals("Cl")) {
              radiusTarget = 0.99;
          } else if (symbol.equals("Br")) {
              radiusTarget = 1.14;
          } else if (symbol.equals("I")) {
              radiusTarget = 1.33;
          } else if (symbol.equals("H")) {
              radiusTarget = 0.30;
          } else if (symbol.equals("C")) {
              if (maxBondOrder == IBond.Order.SINGLE) {
                  // Csp3
                  radiusTarget = 0.77;
              } else if (maxBondOrder == IBond.Order.DOUBLE) {
                  radiusTarget = 0.67;
              } else {
                  radiusTarget = 0.60;
              }
          } else if (symbol.equals("O")) {
              if (maxBondOrder == IBond.Order.SINGLE) {
                  // Csp3
                  radiusTarget = 0.66;
              } else if (maxBondOrder != IBond.Order.SINGLE) {
                  radiusTarget = 0.60;
              }
          } else if (symbol.equals("Si")) {
              radiusTarget = 1.11;
          } else if (symbol.equals("S")) {
              radiusTarget = 1.04;
          } else if (symbol.equals("N")) {
              radiusTarget = 0.70;
          } else {
              radiusTarget = 0;
          }
          return radiusTarget;
      }
docs: Gets the covalentRadius attribute of the InductivePartialCharges object.
  
  @param  symbol        symbol of the atom
  @param  maxBondOrder  its max bond order
  @return               The covalentRadius value given by the reference