CC of excited B1 open-shell singlet of MgNe

Dear All,
I am carrying out preliminary CC calculation on MgNe using MRCC 25.1.4.
Everything went ok for the X 1_SIGMA_+ ground state and the A 3_PI_0 states (I calculated B1 and B2 triplets, both belong to the PI irrep in Cxv)
Then I tried the C 1_PI states (both B1 and B2): the UHf calculation seems ok, but right at the start of the CCSDT calculation I got and "Invalid spatial symmetry!" error message.
I also noticed that the UHF expectation value of S^2 = 1.0001, which does not seem a good omen.
I attach the input and output files.
Thank you in advance for any help.
Best,
Alessandro


INPUT
#
calc=CCSDT
core=2
basis=aug-cc-pVTZ
scftype=uhf
symm=B1
occ=7,2,2,0/6,3,2,0
mem=3000MB
ccprog=mrcc
cctol=10
scftol=14
scfdtol=14
itol=15

tprint=0.01
verbosity=3

charge=0
mult=1
unit=angs
geom
Mg
Ne 1 R

R=3.15

 

Dear Alessandro,
It is not possible to converge the CC equations to an excited state. Please use linear response CC starting from the ground-state CC solutions.

Dear Mihaly,
thanks for the suggestion, I'll try with LR-CC.
Best,
Alessandro