Wavefunction for a monoatomic molecule

1

I’d like to calculate energy, homo, lumo, etc, of a monoatomic molecule such as Ar Xe Ne… So I’d like to get a wavefunction for them, Is it possible ?

When doing the following, I got error, please advice me.

energy, wf = psi4.optimize(level, molecule=monoatomic_molecule, return_wfn=True)

ValueError: not enough values to unpack (expected 2, got 0)

2

Thanks for the bug report. I’ve added this to the list.

In the meantime, use psi4.energy rather than psi4.optimize for single-atom molecules.

3

Thanks for the comment.
by the way. psi4.energy is available for HOMO, LUMO, etc?

4

No, psi4.homo and psi4.lumo do not exist.

Whatever procedure you use to get the energy from psi4.optimize will work with psi4.energy. Probably, you’re setting return_wfn=True and reading the orbital energies from the wavefunction object.

5

Thanks for the additional your reply.
Yes, I use wavefunction.

I wait bug fix!
best!

6

Accordig to the discussion here Single-Atom Optimization Not Intercepted · Issue #2971 · psi4/psi4 · GitHub

Bug seems not to be critical, and it is just a printing issue,
So, I run the code to get energy, but, I met the error below
Is it actully possible to get a wavefunction from Ar moleclue?
Sorry for my beginner question.

if len(mol.GetAtoms())>1:
    psi4.optimize(level, molecule=molecule)
energy, wf = psi4.energy(level, molecule=molecule, return_wfn=True)

23968
     RDKit          2D

  1  0  0  0  0  0  0  0  0  0999 V2000
    2.0000    0.0000    0.0000 Ar  0  0  0  0  0 15  0  0  0  0  0  0
M  END

mol_input = 0 1
 Ar 0.0 0.0 0.0
>>>>>
[16:55:49] UFFTYPER: Unrecognized atom type: Ar3+4 (0)
[16:55:49] SMILES Parse Error: syntax error while parsing: Ar
[16:55:49] SMILES Parse Error: Failed parsing SMILES 'Ar' for input: 'Ar'
---------------------------------------------------------------------------
ArgumentError                             Traceback (most recent call last)
File <timed exec>:91

ArgumentError: Python argument types in
    rdkit.Chem.rdmolops.AddHs(NoneType)
did not match C++ signature:
    AddHs(RDKit::ROMol mol, bool explicitOnly=False, bool addCoords=False, boost::python::api::object onlyOnAtoms=None, bool addResidueInfo=False)
7

This error has nothing to do with Psi4. Go ask rdkit developers.

8

Sorry for this additional email. I successfully got a wave function of Ar.

But I have another question on wavefuntion I got.

With hf/sto-3g, psi4.energy() can not give me HOMO KUMO, etc, I got error as follows

energy, wf = psi4.energy(level, molecule=molecule, return_wfn=True)    
#homo/lumo  
LUMO_idx = wf.nalpha()  
HOMO_idx = LUMO_idx - 1   
print(LUMO_idx, HOMO_idx) # 9, 8   
homo = wf.epsilon_a_subset("AO", "ALL").np[HOMO_idx]   
lumo = wf.epsilon_a_subset("AO", "ALL").np[LUMO_idx]   

[-117.26363060  -12.05489692   -9.30838973   -9.30838973   -9.30838973  
 -1.15443386   -0.49593635   -0.49593635   -0.49593635]
IndexError: index 9 is out of bounds for axis 0 with size 9

But, for instance, with mp2/6-31G(d)
I can get HOMO, LUMO values with above code

[-118.60045327  -12.31830051   -9.56950805   -9.56950805   -9.56950805
 -1.27470938   -0.58893903   -0.58893903   -0.58893903    0.60248449
 0.72598190    0.72598190    0.72598190    1.21780529    1.21780529
 1.21780529    1.21780529    1.21780529    4.87327189]

Why hf/sto-3g provides only 9 outputs, Where can I refere on this things?

9

Read any introductory quantum chemistry textbook that covers basis sets. This is a consequence of STO-3G being a minimal basis set.

10

Thank you for the comment.
I did not know taht the outputs are based on some theory on quantum chemistry.
I start to check some text book.

11

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