I'm using WebMO to construct molecules that have high multireference character, but I cannot seem to find any, or perhaps I'm not building them correctly on WebMO; I know singlet biradicals generally have high MR character, but when I carry out a CI calculation on them, the weight of the Hartree-Fock configuration is extremely high (1/Norm(A) value). I've carried out CI calculations on TMM, TME, p-quinodimethane, but these do not exhibit high MR character using my diagnostic of looking at the weight of the HF configuration in a CI calculation.
Can anyone suggest any medium-sized molecules that exhibit high MR character?
#N CI/6-31G(d) SP
C4H6
0 1
C
C 1 B1
C 2 B2 1 A1
H 3 B3 2 A2 1 D1
H 3 B4 2 A3 1 D2
C 2 B5 1 A4 3 D3
H 6 B6 2 A5 1 D4
H 6 B7 2 A6 1 D5
H 1 B8 2 A7 3 D6
H 1 B9 2 A8 3 D7
B1 1.322324000
B2 1.469933386
B3 1.089341949
B4 1.089341949
B5 1.469933386
B6 1.089341949
B7 1.089341949
B8 1.087824972
B9 1.087824972
A1 148.4186871
A2 118.9917788
A3 118.9917788
A4 148.4186871
A5 118.9917788
A6 118.9917788
A7 121.5429429
A8 121.5429429
D1 73.31395214
D2 -73.31395214
D3 -180.0000000
D4 -73.31395214
D5 73.31395214
D6 180.0000000
D7 -0.000000000