I have a wavefunction from an energy calculation with return_wfn=True. There is a Da function in the wavefunction class that returns the alpha density matrix. If I write

dm = wfn.Da()

or

dm = np.array(wfn.Da())

I expect to get the density matrix as a Psi4 matrix or numpy array. However either seems to be silently executed with a null result. What is the correct syntax?

# What is the syntax for the Da function?

**ajs**#1

**hokru**#2

`Da`

returns a psi4 Matrix class. If this matrix has irreps, simple `np.array()`

conversion does not work.

Then you can use the general way:

`dm = wfn.Da().to_array()`

**ajs**#3

Thank you; I don’t want it separated into irreps, but using “symmetry C1” gives me what I want.