3. Deviations in the Singlet-Triplet (S-T) Gaps (in kcal/mol) of Biradicals, Computed by NEVPT2, AC0, and NEVPTS with aug-cc-pVTZ (AVTZ) and aug-cc-pVQZ (AVQZ) .
| biradical |
active space |
NEVPT2 |
AC0 |
NEVPTS |
EOM-CC
|
|||
|---|---|---|---|---|---|---|---|---|
| AVTZ | AVQZ | AVTZ | AVQZ | AVTZ | AVQZ | |||
| C4H4 | CAS(4,4) | –3.53 | –3.54 | –4.23 | –4.24 | –4.14 | –4.14 | 4.20 |
| C5H5 | CAS(5,5) | –3.51 | –3.46 | –5.56 | –5.51 | –3.37 | –3.32 | –13.88 |
| C4H3NH2 | CAS(6,5) | –3.91 | –3.84 | –4.63 | –4.64 | –4.53 | –4.53 | 2.65 |
| C4H3CHO | CAS(6,6) | –3.27 | –3.28 | –3.69 | –3.71 | –3.80 | –3.81 | 3.65 |
| C4H2NH2(CHO) | CAS(8,7) | –9.14 | –9.16 | –9.03 | –9.04 | –9.58 | –9.59 | 5.68 |
| C4H2-1,2-(CH2)2 | CAS(6,6) | –0.20 | –0.13 | 2.13 | 2.22 | 1.53 | 1.62 | 77.68 |
| C4H2-1,3-(CH2)2 | CAS(6,6) | –0.82 | –0.75 | –2.72 | –2.64 | –0.42 | –0.34 | –18.49 |
| MD | –3.48 | –3.45 | –3.47 | –3.94 | –3.47 | –3.45 | - | |
| MAD | 3.48 | 3.45 | 4.57 | 4.57 | 3.91 | 3.91 | - | |
a
The DEA-EOM-CC/AVTZ results (EOM-CC) reported by Gagliardi and co-workers are used as the reference.
b
The mean deviations (MD) and mean absolute deviations (MAD) relative to EOM-CC results are given as well.