Convert sheet resistance and thickness to Sigma correctly

Use consistent units

For a uniform thin film, Sigma = 1 / (sheet resistance × thickness). Express thickness in the model's length unit. With micrometre units, the result is in ohm^-1 micrometre^-1.

A generic example: sheet resistance 2 ohm/square and thickness 0.1 micrometre give Sigma = 5 ohm^-1 micrometre^-1. These are illustrative values, not a recommended fabrication process.

Check the active material model

A per-layer value can override the global Sigma. The manual also states that defining Lambda for a layer makes Sigma and MuR inactive for that layer. Confirm the intended normal-conductor or superconducting model before interpreting a conductivity change.

Verify

Inspect the effective process definition and use a simple resistive example to check units and geometry. A plausible Sigma does not prove that the contacts and current path are correct.