13.6 Comments on the Output

• The most important output for rirpa are the Hartree-Fock (HXX) energy and the RIRPA correlation energy which are written to the standard output.

• The optimal scaling parameter for the quadrature grid is printed together with a sensitivity parameter. The sensitivity parameter provides a numerical estimate for the error in the numerical integration used to evaluate \(E^{\text{C RIRPA}}\). Experience demonstrates that the sensitivity parameter correlates well with the condition number of the matrix \(\mathbf{Q}\). Small gap systems have large condition numbers and therefore require large grids. An estimate of the number of eigenvalues smaller than \(0.05\) H is given and if necessary, a warning to increase the grid size is printed to standard output.

• The molecular dipole and quadrupole moments are written to the standard output whenever a gradient calculation is carried out.

• Rotational constants are provided in the rirpa output below the coordinate section.

• Enabling the option rpaprof will output additional timings information.