In transient simulation, we often apply a nonzero bias voltage at one or more contacts at t=0. The solver then first has to initialize by getting the steady state solution for the system for that bias voltage before starting the transient simulation. If the voltages at t=0 are large then the solver may have a hard time reaching that initial solution.
To help the solver and to make the initialization faster, we can first perform a steady state simulation to sweep the bias voltages from 0 V to the desired value at t=0 and use the result of that simulation to initialize the transient simulation. We can do this by using the “Continue from Previous Solution” option in the CHARGE solver.
In the transient simulation file, we need to choose the project file with the steady state simulation result as the continuation file. The solver will then load the result of the last bias point from the project file (of the steady state simulation) and use that to initialize the transient simulation instead of trying to calculate the result from scratch.