Keyword

Options:

Auxis | The auxiliary function set string Auxis defines the global auxiliary function set. If this option is absent, the GEN-A2 auxiliary function set is used by default. |

Similar to the orbital basis set options, the auxiliary function sets can also be assigned to individual atoms by the atomic symbol or to atom groups by the element symbol in the keyword block of AUXIS. The syntax and hierarchy of these assignments is analogous to the orbital basis set assignments (see 4.3.1). For CH (see input in 4.1.1) the following auxiliary function definition

AUXIS (A2) C (GEN-A2*) C1 (GEN-A2)

assigns a GEN-A2 auxiliary function set to atom C1, a GEN-A2* auxiliary
function set to the other carbon and the A2 auxiliary function set to all other
atoms. The `AUXIS` file of deMon contains only the A2 auxiliary function set.
The other auxiliary function sets used above (`GEN-A2` and `GEN-A2*`) are
generated automatically [133,156] according to the procedure described
in Appendix A. The GEN-An+ () auxiliary function sets are
particular for the variational fitting of Fock exchange. They have a set structure
as the corresponding GEN-An* auxiliary function sets but without the angular
momentum index augmentation to and Hermite Gaussians during the SCF
iterations. Instead, this augmentation is only performed post-SCF for the final
Fock energy calculation. Thus, the computational demand for the GEN-An+ auxiliary
function set during the SCF is close to that of GEN-An, whereas the final
(non-variational) energy is close to GEN-An*. Just as with the orbital basis sets,
auxiliary function sets can also be specified directly in the input file using the
format:

Auxis SYMBOL Read LMAX EXPONENT : : LMAX EXPONENT

Here `LMAX` denotes the maximum angular momentum quantum number
of the auxiliary function subset and `EXPONENT` the exponent which is shared
[53,54] by all functions in that subset. Thus an auxiliary function
subset with
contains ten functions, namely one , three
and six (Cartesian) functions. In deMon2k, these functions are primitive
Hermite Gaussians [51,157] of the form (without normalization):

(7) |

Multiplicity 3 SCFType ROKS VxcType Basis BLYP Mixing 0.4 PRINT GTO CGTO AUXIS Geometry Z-Matrix O O O r # Variables r 1.207 BASIS O Read 1 0 2 49.98097100 0.4301280000 8.896588000 0.6789140000 2 0 2 1.945237000 0.4947200000E-01 0.493363000 0.9637820000 2 1 2 1.945237000 0.5115410000 0.493363000 0.6128200000 AUXIS O Read 0 100.0 0 25.0 2 5.0 2 1.0

The auxiliary function set in this example consists of two and two sets. Together these comprise 22 auxiliary functions (1+3+6 from each set and 1 from each set).