How to specify several reference configurations for MRCI on HF orbitals

Hello,

I would like to do a MRCISD calculation with several reference configurations generated by removing one electron from an occupied HF orbital. To make it clear how the reference configurations are generated, for H2O, for example, there would be 4 reference configurations:

2221
2212
2122
1222

with 1s of O being excluded (frozen).
Is it possible to specify such a reference space?

Kind regards,
Evgeniy

Dear Evgeniy,
Do you have an ROHF for H2O+? Then you should just set:
nacto=7
nactv=1

Dear Mihaly,

Many thanks for your response!
Actually, I want to use RHF (closed-shell) orbitals of the neutral H2O and do MR-CISD for H2O+.
I tried the following input:

calc=cisd
refdet=serialno
1-3
4

active=serialno
1-4
symm=2
verbosity=3
basis=6-31G
nstate=2
unit=bohr
geom
H
O 1 R1
H 2 R1 1 A

R1=2.00000000000
A=104.2458898548


And it seems to work.
In principle,

nacto=7
nactv=1

instead of

active=serialno
1-4

should give the same result (the same total number of determinants), but somehow it does not (gives a different number of determinants), which is strange. But maybe I am misunderstanding something?

Kind regards,
Evgeniy

Dear Evgeniy,
Thank you for reporting this. Please download the new patches, which fix this problem.

Dear Mihaly,

I have downloaded the new xmrcc.f (which, I guess, is the patch) and recompiled the package. After having re-run the same jobs I, however, did not see any difference compared to the previous results.
(I guess the patch is included in the tar-ball mrcc.2022-03-18.tar.)

Kind regards,
Evgeniy

Dear Evgeniy,
You should download the following files:
minp.f mrcc.f goldstone.f xmrcc.f ovirt.f combin.f mrcc xmrcc goldstone mrcc_mpi xmrcc_mpi ovirt dmrcc dmrcc_mpi minp