The CASTEP Analysis dialog can be used to generate plots of the change in electrostatic potential through a slab, which is related to the energy required to remove an electron from the bulk into the vacuum (the work function). The plots are created by averaging the electrostatic potential in the planes perpendicular to the slab normal.
Work function can only be calculated for structures constructed in a slab geometry so that they contain atomic planes separated by a vacuum layer.
If nonlocal exchange was used for the calculation local potentials are poorly defined and are not available for analysis.
The averaged electrostatic potential is reported along the fractional coordinate of the unit cell in the direction of the vacuum. The Fermi level is reported on the work function chart.
To create an averaged potential chart
seedname Potential Profile.xcd, is created in the results folder and becomes the active document. The selected potential field is imported into the 3D Atomistic document and may be displayed as an isosurface.
Analyzing CASTEP results
Visualizing volumetric data