# CONVIV online manual

- CONVIV is the acronym for CONtracting VIbrations Variationally.

It allows one to perform an arbitrary number of successive contracted configuration interactions for mean field Hamiltonians corresponding to user-defined partition of the system degrees-of-freedom (VMFCI method). There is no limitation on the number of degrees of freedom and no constraint on the design of hierarchical contraction schemes, except that:

- The partition of step n+1 must be coarser or equal to that of step n
- A maximum of 15 degrees-of-freedom can be contracted together at any one step

Remark: At step 0, degenerate degrees-of-freedom are automatically contracted together in order to preserve symmetry, but this constraint can be bypassed by defining the degenerate degrees-of-freedom as non-degenerate.

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Last modified on Jun 27, 2019 3:00:53 PM