So, I have two electrodes in my structure. The structure is given in the attached file. Basically, it shows a copper anode (blue) on top and a copper cathode (blue) at the bottom -- at a distance of 200 Angstroms. The bottom cathode has a spherical cavity close to the surface. Cathode is grounded and anode voltage is 10 V, yielding an "average" field of 5e8 V/m. Since the cavity is close to the cathode surface, there is a very thin "covering" of copper.
The sphere inside the copper cathode is of radius 10 angstroms and centered at (0,0,39.22) angstroms. The bottom surface of the cathode is at z = 0 angstroms and the top surface is at 54.22 angstroms. So, the center of sphere (hole) is at a depth of 39.22 A, and has a radius of 10 A ==> the top of the hole is at 49.22A. This leaves 54.22-49.22 = 5 A thin slab above the hole roughly. Process used to create spherical void/hole: I created the copper slab first, then the sphere and used the difference boolean operator to remove the sphere from the copper slab/block. (This is the correct process to create the void I hope?) In case of the space between the cathode and anode, I created another block between these and assigned its material to air.
I find no field in the cathode. I was thinking that since the "cover" above the sphere is so small (Angstrom scale), some E-field penetration could be expected even if the cathode is a metal (Copper).
I was wondering if my use of the built-in model or boundary conditions lead me to E=0 in the metal? Or is it real and the field should indeed be zero?
Also, attaching my model herewith.