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For RI-CC2 calculations,
the operation count and thereby the
CPU and the wall time increases--as for RI-MP2 calculations--approximately
(O2V2Nx), where O is the
number of occupied and V the number of virtual orbitals
and Nx the dimension of the auxiliary basis set for
the resolution of the identity.
Since RI-CC2 calculations
require the (iterative) solution of the cluster
equations (9.5) and (9.6), they are about 10-20 times more
expensive than MP2 calculations.
The disk space requirements are approximately
O(2V + N)Nx + Nx2 double precision words.
The details of the algorithms are described in ref. , for
the error introduced by the RI approximation see