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5 votes
Accepted

What is the correct way to set up occupation for single atom in CFOUR software?

Your setting is incorrect for the dominant Slater determinant when calculating the electronic ground state of an O atom: OCCUPATION=2-1-1-1-0-0-0-0/2-1-0-0-0-0-0-0 ...
Nike Dattani - No Free Time's user avatar
4 votes

How to remove f functions from a cc-pVQZ basis set in CFOUR format?

If you use the Basis Set Exchange anyway, I recommend you have a look at the Python library which makes it quite simple to modify basis sets in any way you want. The code below does what you want but ...
Susi Lehtola's user avatar
  • 19.7k
3 votes
Accepted

How to remove f functions from a cc-pVQZ basis set in CFOUR format?

The CFOUR basis format is laid out on their website, but it might be in a little more detail and a little more abstract than you need, so I'll walk through your example of Boron cc-pVQZ to make it ...
Tyberius's user avatar
  • 15.5k
3 votes
Accepted

When orbitals are labeled based on their irreps in D2h, how are the orbitals ordered for an N atom?

"Nitrogen atom has a point group of Dinfh, but ⁠CFOUR uses a lower symmetry of D2h instead" The point group of the N atom (or any atom) is $K_h$, not $D_{\infty_h}$, the latter would be ...
Nike Dattani - No Free Time's user avatar
2 votes

Which programs can calculate corrections to the Born-Oppenheimer approximation?

CFOUR + MRCC You asked about MOLPRO and Psi4. As recently as 2021, DBOC (diagonal Born-Oppenheimer correction) wasn't implemented in Psi4. The same is true for MOLPRO. No other types of Born-...
Nike Dattani - No Free Time's user avatar
1 vote

MRCC/CFOUR interface bug for a single atom calculation?

The MRCC interface with CFOUR does work on individual atoms, even for DBOC calculations. For example, I did a DBOC calculation at CCSDTQ level for the carbon atom here. The input file for that ...
Nike Dattani - No Free Time's user avatar
1 vote

Crash of DF-CCSD or DF-CCSD(T) geometry optimization (MRCC package)

The MRCC manual suggests that analytic gradients are not available for CCSD(T), they are only available for the following 12 categories of methods: 6.2 Geometry optimizations and first-order ...
Nike Dattani - No Free Time's user avatar

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