Cutoff Energies

The following two variables for the energy cutoffs are mandatory, and have no default value. All energies are in Rydbergs.

energy_cutoff             Cutoff for the Hamiltonian matrix
submatrix_energy_cutoff   Cutoff for the submatrix to be used for the
                          generation of the starting guesses.

Example:

energy_cutoff           70
submatrix_energy_cutoff 10

Your energy_cutoff will depend on your pseudopotential, and generally you can simply use a submatrix_energy_cutoff of 5 to 10 Ry with no problem.

Advice: take the submatrix cutoff about 1/5 of the energy_cutoff, but never larger than about 10 Rydbergs. The generation of the starting guess is not optimized, and can become very time consuming if the submatrix is too large. Also, the memory requirements increase rapidly with submatrix_energy_cutoff, because the full submatrix is kept in memory.