Dear Psi4 developers and users,

I have done a `B3LYP`

calculation first on a mixed basis set named `LACVPs`

, with metal using `LANL2DZ`

and other elements using `6-31G*`

. Then I would like to feed the converged wavefunction (`npy`

file) of `B3LYP/LACVPs`

for a calculation of a different basis set, say `B3LYP/def2-SVP`

, to ensure the two calculations converge to the same electronic state. However, the new `B3LYP/def2-SVP`

calculation is really hard to converge and finally converge to a completely different electronic state (`B3LYP/def2-SVP`

has a `<S^2> `

of 4.61 (absurdly high) and `B3LYP/LACVPs`

has a `<S^2> `

of 1.16, where the expected `<S^2> `

=0.75). I also did another controlled experiment to narrow the range of this problem to the basis set projection with ECP, here specifically `LANL2DZ`

. I define a new mix basis named `DEFCVPs`

, with metal using `LANL2DZ`

and other elements using `def2-SVP`

. Then I repeat the procedure of feeding the `npy`

file of `B3LYP/LACVPs`

for a new calculation of `B3LYP/DEFCVPs`

. This time the calculation proceeds well and converges to the same electronic state and has a `<S^2> `

of 1.15). Any ideas about why this happens would be appreciated. Thank you!

PS: I have attached the two output files just in case anyone is interested to look at them.

Best,

Chenru

output-lacvps-def2svp.dat (25.2 KB) output-lacvps-defcvps.dat (21.2 KB)