Use the charge density from the zero-field calculation as the starting density for
SCF calculations with applied fields. For small fields, this will be fastest.
If there is trouble converging with larger fields, set to false,
to initialize the calculation for each field from scratch, as specified by the LCAO variables.
Only applies if ResponseMethod = finite_differences.
Write density after each calculation for restart, rather than just the resulting electronic dipole moment.
Only applies if ResponseMethod = finite_differences. Restarting from calculations at smaller
fields can be helpful if there are convergence problems.