I am facing a problem running the DETCI module for the 7-zeta basis set. The input file is:
memory 40 gb
C 0. 0. 0.
The DETCI module crashes at the “==> Setting up CI strings <==” step with the message (in fact, some 10^6 messages):
(subgr_lex_addr): Impossible walk!
There are 104941 alpha and 267 beta strings
The CI space requires 67188 (6.72E+04) determinants and 16 blocks
The calculation with the 6-zeta basis sets yields fine results. Also, the 7-zeta HF energy looks fine.
I would greatly appreciate any advice.
Yes, a check for >256 active orbitals will be added to the driver so that it fails gracefully.
It could definitely be rewritten, but detci is really not optimized for cisd, cisdt, etc., and the limitation doesn’t impede detci’s strengths. For purpose-written cisd in psi4, there is the fnocc module (default for RHF), but it’s RHF-only.
Neither, I’m afraid. I think storage is too valuable in detci to double the size for a nice but untargeted method, cisd, and fnocc is Eugene DePrince’s code, and his research has moved on. For open-shell at the same gross level, all I can offer is lccd and ccsd.