TABLE III.
Energy gaps of 1,3-butadiene conformers calculated with respect to the s-trans conformer are reported, without considering zero point energy corrections, and referring to the PES reported in Figure 2. The QMC calculations are done on the geometries reported in Tables I and II, with ECP pseudopotential.
|
TS1 (kcal/mol) |
gauche (kcal/mol) |
s-cis (kcal/mol) |
|
|---|---|---|---|
| VMC1 | 6.06(17) | 2.69(16) | 3.54(19) |
| vmc2 | 6.68(11) | 3.28(11) | 3.68(11) |
| LRDMC1 | 6.31(31) | 2.72(30) | 3.84(30) |
| LRDMC2 | 6.46(28) | 3.14(29) | 3.94(29) |
| HFa | 6.23 | 3.51 | 4.34 |
| CCSD(T)b | 6.124 | 2.899 | 3.474 |
| CCSD(T)c | 6.405 | 3.011 | 3.489 |
| CCSD(T)a | 6.06 | 3.05 | 3.43 |
| G2d | 5.67 | 2.92 | 3.45 |
| CBS-Qd | 6.02 | 3.16 | 3.38 |
| MP2b | 6.496 | 2.899 | 3.697 |
| MP2a | 6.53 | 3.02 | 3.65 |
| B3LYPe | 7.54 | 3.97 | |
| UVf | 3.02(1) | ||
| RS (ECR)g | 5.93 | 2.85 | 4.00 |
| GF-RS (A)h | 6.456 | 2.951 | 3.468 |
| GF-RS (B)h | 5.684 | 3.091 | 4.254 |
HF calculations are done with a cc-pVQZ basis while MP2 results are extrapolated and CCSD(T) results are obtained with a cc-pVDZ basis set. Reference 22.
Both calculations done with cc-pV5Z basis set from Ref. 27.
CCSD(T)(FC)/CBS with core/valence, scalar relativistic and CCSDT(Q)(FC)/cc-pVDZ corrections from Ref. 29.
G2 is based on QCISD(T)/6-311+G(3df,2p) calculations on anMP2/6-31G* evaluated geometry, CBS-Q is based on MP2/6-311++G(3df,2p) calculations with higher order corrections from MP4(SDQ)/6-31+G(2d,p) and QCISD(T)/6-31+G on MP2/6-31G* geometries, both from Ref. 20.
Calculations with TZVP basis from Ref. 25.
The value of 2.93(1) reported in Ref. 78 is the ΔH° value obtained through UV spectra. To this value we have added the zero point energy difference between the gauge and s-trans state obtained in Ref. 29 through CCSD(T)(FC) calculations (+0.09 kcal/mol).
Raman Spectra from Ref. 30.
Gas Phase Raman Spectra (25°-200°) from Ref. 31.