# vibanal_wfn

`psi4.driver.``vibanal_wfn`(wfn, hess=None, irrep=None, molecule=None, project_trans=True, project_rot=True)

  Function to perform analysis of a hessian or hessian block, specifically… calling for and printing vibrational and thermochemical analysis, setting thermochemical variables, and writing the vibrec and normal mode files.

  Parameters:

  - wfn (`Wavefunction`) – The wavefunction which had its Hessian computed.
  - hess (ndarray of float, optional) – Hessian to analyze, if not the hessian in wfn. (3*nat, 3*nat) non-mass-weighted Hessian in atomic units, [Eh/a0/a0].
  - irrep (int or string) – The irrep for which frequencies are calculated. Thermochemical analysis is skipped if this is given, as only one symmetry block of the hessian has been computed.
  - molecule (`Molecule` or qcdb.Molecule, optional) – The molecule to pull information from, if not the molecule in wfn. Must at least have similar geometry to the molecule in wfn.
  - project_trans (boolean) – Should translations be projected in the harmonic analysis?
  - project_rot (boolean) – Should rotations be projected in the harmonic analysis?

  Returns: | vibinfo – A dictionary of vibrational information. See `harmonic_analysis()`
  Return type: | dict