I’ve calculated a stretched water molecule at CASSCF(4,4)/def2-TZVP level, using PSI4, PySCF, ORCA, etc. CASSCF energies (-75.9350695 a.u.) from various programs match excellently.
However, if the density fitting (RI-JK using def2-universal-jkfit as auxbasis) is turned on, the result of PSI4 is slightly different from others:
PySCF, ORCA: -75.9350735 a.u.
PSI4: -75.9350878 a.u.
The CASSCF convergence is smooth. Is there any threshold that controls the DF accuracy? PSI4 Files are attached.
00-h2o_cc-pVDZ_1.5_uhf_uno_asrot2gvb4_s.A.txt (56.0 KB) a_inp.txt (2.4 KB) a_out.txt (16.5 KB)
Thanks! By the way, I’m using Psi4 1.4a2.dev549.