Debug
The key DEBUG is used to generate extensive output that is usually only relevant for debugging purposes. It operates exactly like the PRINT key but there is no converse: nodebug is not recognized; it would be irrelevant anyway because by default all debug print switches are off.
A list of the possible items for the DEBUG key is given below.
All items of the print list can also be used with the debug key. If they are not mentioned in table III, the meaning is the same as for the print key, but the corresponding output may be generated more often, for instance at every SCF cycle rather than at the last one only.
| Item | Explanation |
| Basis | Construction of the orthonormal LOW basis from elementary (BAS) and fragment (FO) basis. |
| Core | Core Orthogonalization procedure |
| Ekin | Kinetic energy matrices. (compare the print switches EKIN) |
| Fit | Construction of the symmetry adapted fit functions |
| Fitint | Construction of integrals used in the Fit procedure. |
| FmatSFO | Requests printing of the SFO overlap matrix in addition to the Fock matrix. This overlap matrix must be identical to the one printed in the results section of the output. This way one makes sure that the AO to SFO transformation of the Fock matrix has been carried out properly. |
| Freq | Force matrices processed in the computation of frequencies: Cartesian and internal representation, before and after symmetrization, etc. (as far as applicable). |
| GeoStep | Geometry optimization procedure. All relevant items. |
| Hess | Complete eigensystem of the Hessian during geometry optimizations. |
| NumInt | Numerical integration. Very extensive output (including the coordinates and weights of all generated points). |
| Pmat | P-matrix (density matrix) during SCF and in the ETS analysis program in the BAS representation. |
| Rhofih | Computation of fit coefficients during the SCF. |
| SCF | Extensive output during the SCF procedure about many different items. See also EPRINT, subkey SCG. |
| SDIIS | All data concerning the DIIS as used during the SCF. See ERPRINT, subkey SDIIS. |
| TransitionField | The Transition State procedure to compute and analyze certain terms in the bonding energy. The distinct components, the involved transition field Fock matrices, etc. |
| Table III. Arguments for the print key DEBUG. All debug switches are by default off. | |
