FCIDUMP of different version

I want to use FCIDUMP module,here is my input.dat

molecule {
0 3
         N 0 0 0
         N 0 0 1.12079733

set {
  basis cc-pVDZ
  reference     uhf

E, wfn = energy('scf', return_wfn=True)


but the result of vesion1.6 and version1.2 are different,is this normal?

We’ve changed the FCIDUMP code between 1.2 and 1.6, so differences are expected. Changes I’m aware of include changes to symmetry handling, frozen orbitals, and whitespace. For a system with degenerate orbitals, it’s also possible that 1.2 and 1.6 converge onto the same solution but with orbitals that differ by a rotation among degenerate orbitals, which could lead to different integrals. This is, however, not going to affect energies of most electronic structure methods, e.g., SCF and FCI.

If you have a specific reason to believe there’s a problem, let us know, and we can investigate.

1 Like

this is enough to my problem,thanks a lot

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