While trying to reproduce some gaussian calculations with psi4, I noticed that the frequecies dependent on the dertype setting for the version of psi4 I am using:

`$ rpm -qif /usr/bin/psi4 | egrep '^Version|^Source'`

`Version : 1.1`

`Source RPM : psi4-1.1-2.add49b9git.fc26.src.rpm`

Is this as expected? I whould expect the frequencies to be more or less the same. The input file I used is:

```
molecule h2o {
units angstrom
H 0.000000 0.760300 -0.196100
O 0.000000 0.000000 0.392200
H 0.000000 -0.760300 -0.196100
}
set basis 6-311G**
set e_convergence 9
set g_convergence gau_verytight
set scf_type pk
optimize('scf', molecule=h2o)
scf_e, scf_wfn = frequencies('scf', dertype='energy', return_wfn=True)
scf_e, scf_wfn = frequencies('scf', dertype='gradient', return_wfn=True)
scf_e, scf_wfn = frequencies('scf', dertype='hessian', return_wfn=True)
```

And the generated freqs:

```
$ grep -A 3 'Vib. Freq' 'hf-6-311Gstarstar-freq.out'
No. Vib. Freq. [cm^-1] Vib. Temp. [K]
1 1750.943 2519.214
2 4142.104 5959.557
3 4237.400 6096.666
--
No. Vib. Freq. [cm^-1] Vib. Temp. [K]
1 1750.925 2519.188
2 4142.111 5959.567
3 4237.427 6096.704
--
No. Vib. Freq. [cm^-1] Vib. Temp. [K]
1 1731.766 2491.623
2 4136.243 5951.124
3 4232.474 6089.579
```

The freqs generated by gaussian are:

`Frequencies -- 1750.9454 4142.1029 4237.3716`

If someone could clarify this, that would be appreciated.