new feature: multiple items can be deleted in the treeview

main.py

@@ -1160,16 +1160,17 @@ def __init__(self, Visualizer, data_dictionary, parent=None, selection_mode=None
         self.show()
 
     def delete_selected_item(self):
-        index = self.treeview.selectedIndexes()[0]
-        item = self.treeview.itemFromIndex(index)
-        bs_name = item.text(0)
+        indexes = self.treeview.selectedIndexes()
+        items = [self.treeview.itemFromIndex(index) for index in indexes]
+        bs_names = [item.text(0) for item in items]
 
-        del_msg = "Are you sure you want to delete " + bs_name + ' permanently?'
+        del_msg = "Are you sure you want to delete " + ', '.join(bs_names) + ' permanently?'
         reply = QtGui.QMessageBox.question(self, 'Sure to delete?', del_msg, QtGui.QMessageBox.Yes,
                                            QtGui.QMessageBox.No)
 
         if reply == QtGui.QMessageBox.Yes:
-            del self.data_dictionary[bs_name]
+            for bs_name in bs_names:
+                del self.data_dictionary[bs_name]
             self.update_tree()
 
     def export_selected_item(self, code=False):

ocean_handlers.py

@@ -331,7 +331,7 @@ def read_optical_spectrum(self):
 
         width = float(self.optical_spectrum_options['edge width'])
         A0 = float(self.optical_spectrum_options['edge amplitude'])
-        edge_f = lambda E: A0*(scipy.special.erf((E - Ek) / width) + 1)/2 / (E / Ek) ** 3
+        edge_f = lambda E: (scipy.special.erf((E - Ek) / width) + 1)/2 / (E / Ek) ** 4
 
         region = E.max()-E.min()
 
@@ -341,7 +341,7 @@ def read_optical_spectrum(self):
         edge = edge_f(E_plot)
         exaf_interp = np.interp(E_plot, E, data[:, 1], left=0)
 
-        res_abs = exaf_interp + edge
+        res_abs = A0*(exaf_interp + edge)
         # c = 299792458
         # omega = E_plot*e/hbar
         # eps2 = res_abs*1e6*c/omega