Function to compute harmonic vibrational frequencies.
Aliases :  frequencies(), freq() 

Returns:  (float) Total electronic energy in Hartrees. 
Note
Analytic hessians are not available. Frequencies will proceed through finite differences according to availability of gradients or energies.
Caution
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Parameters: 


Examples : 
>>> # [1] <example description>
>>> <example python command>
>>> # [2] Frequency calculation for b2 modes through finite difference of gradients
>>> frequencies('scf', dertype=1, irrep=4)