Gaussian 03 Online Manual
Last update: 2 October 2006

Sparse

Use sparse matrix storage for performance enhancement of large calculations (above around 400 atoms) [34]. The keyword's option allows you to specify the cutoff value for considering matrix elements to be zero.

Loose
Sets the cutoff to 5 * 10-5.

Medium
Sets the cutoff to 5 * 10-7. This is the default for semi-empirical methods.

Tight
Sets the cutoff to 1 * 10-10. This is the default for DFT methods.

N
Sets the cutoff to 1 * 10-N.

Energies and gradients for AM1, Hartree-Fock and DFT methods (closed shell calculations). It is useful for AM1 calculations of more than 200 atoms. This keyword may also be used within method specifications for ONIOM layers.

FMM