# CONVIV online manual

*Color(white, green, CONVIV)? is the acronym for Color(white, green, CON)?tracting Color(white, green, VI)?brations Color(white, green, V)?ariationally.

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.