The first tab (Figure ) contains three side-by-side windows showing the projected phase stability region, defect formation energy diagram, and the temperature-dependent carrier concentration of the selected material, depending on which data is available. The chemical potential axes of the phase diagram can be changed using the dropdown menus located below the diagram. The three diagrams are interconnected through the user-tunable chemical potentials of the elemental species in the material. The user can explore this chemical potential space by clicking on the phase stability window, editing the text boxes, or using the slider (for quaternary compounds, see Section 3.1); the defect formation energy diagram and carrier concentration plot will change accordingly in real time. In the defect formation energy diagram, the user can specify the temperature at which the defects are synthesized (denoted T syn ), which changes the defect concentrations and hence alters the electron and hole concentrations to satisfy the charge neutrality condition (see Section 3.3 for further details). Provided that data for extrinsic defects also exist in Defects_Tracker.json, the user can view how a dopant affects the equilibrium Fermi energy and carrier concentration of the material. The user can specify the ambient temperature in the carrier concentration column to observe how the equilibrium Fermi energy shifts around in the band gap of the material. VTAnDeM plots both electron and hole concentrations rather than the net carrier concentration.