Download Manual for the MRCC Program System

off No local correlation calculation is performed.
on Local correlation calculation is performed.
Note: Local correlation methods can also be run if the prefix “L” is
added to the corresponding option of keyword calc, see the description of calc.
Default: localcc=off
Example: for local correlation calculations give localcc=on
maxact Maximum number of inactive labels. One can impose restrictions
on the cluster operator using this keyword. The maximum number
of virtual/occupied inactive labels on the singly, doubly, ... excited
clusters can be specified.
Options: on or off. If maxact=on, the maximum number of virtual and
occupied inactive labels must be specified in the subsequent line
as an integer vector. The integers must be separated by spaces.
The vector should contain as many elements as the excitation rank
of the highest excitation in the cluster operator. The integers are
maximum number of virtual/occupied inactive labels allowed on
amplitudes of single, double, ... excitations, respectively.
Default: maxact=off
Example: Suppose that we have up to quadruple excitations, and the
single, double, triple, and quadruple excitations are allowed to
have maximum of 1, 2, 2, and 1 inactive virtual and occupied labels, respectively. Then the input file should include the following
lines:
maxact=on
1 2 2 1
maxex Level of highest excitation included in the cluster operator in the case
of MRCI/CC calculations. In an MR calculation all single, double (or
higher) excitations out of the reference determinants are included in
the cluster operator (see the description of keyword nacto), however,
the very high excitations are frequently irrelevant. Using this option
the latter can be dropped. If maxex is set to a positive integer n, only
up to n-fold excitations will be included in the cluster operator. The
excitation manifold can be further selected by imposing constrains on
the number of active/inactive labels of the excitations (see keyword
maxact). See Refs. 2 and 3 for more details.
Options:
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