# WFN_MIX

A section that allows manipulation of the MO coeffs, e.g. for changing a ground state into an excited state. Starting from a copy of the original MOs, changes can be made by adding linear combinations of HOMO/LUMO of the original MOs to the result MOs. This method is called after an SCF optimization or before an RTP run if INITIAL_WFN=RESTART_WFN. Note that if called after an SCF optimization, a restart file with the mixed MOs is saved. This is not the case for an RTP with INITIAL_WFN=RESTART_WFN. [Edit on GitHub]

Subsections

- UPDATE

## Keywords

- OVERWRITE_MOS

## Keyword descriptions

OVERWRITE_MOS: logical = F

  Lone keyword: `T`

  If set to True, the active molecular orbitals in memory will be replaced by the mixed wfn at the end of the wfn mixing procedure. For instance, you can then use this new set of MOs to perform RTP or EMD directly. Note that in the case of an RTP run with INITIAL_WFN=RESTART_WFN, the OVERWRITE_MOS keyword is not used. [Edit on GitHub]