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In the iterative method outlined
above, the super-matrices *A*
and *B*
never need to be set up
explicitly; only the products of *A*
and *B*
with some suitable basis
vectors are required. These matrix-vector-products are evaluated
very efficiently in the AO basis, because the required four-index
integrals can be computed ``on the fly'' and need not be transformed
or stored on disk. In addition, prescreening techniques based on
rigorous bounds are straightforward to apply. This leads to a
low-order scaling
*O*(*N*^{2}) - *O*(*N*)
for the time-determining
steps. Due to the similarity to ground state fock matrix
construction, the same keywords are used to control these steps as
in semi-direct SCF, namely `$thime`, `$thize`,
`$scfintunit`, see Chapter 6. The same is true
for DFT and RI keywords such as `$dft`, `$ridft`,
`$ricore`.

TURBOMOLE M