By uae of ab initio and analytic energy gradient method, twelve optimized electronic states of AICB,AIBC, BAIC in six geometric configurations are determined at all electron UHF(RHF) /6-31G level, their singles and do...By uae of ab initio and analytic energy gradient method, twelve optimized electronic states of AICB,AIBC, BAIC in six geometric configurations are determined at all electron UHF(RHF) /6-31G level, their singles and doubles CI (CISD) energies are also obtained. The Stabillties for the atates of AICB have been investigated based on the vibrational analysis. binding energy and fragmentation energy. The ground state is 3∑+ of AICB (C∞. TAIC= 1.7497.,TBC=1.3511 A = 206.7, 799.5, 1802.9 cm-1, T=0), the second state is 1A' of AICB (Cs,TAIC=1.9162, TBC = 1.3154 A, ∠AICB=179。8307, =238.5, 575. 1,1767. 5.cm-1, T =2432.84 cm-1). The fragmentations of vallous States (fragmentation products are AIB,AIC, BC diatomic clusters. and Al, B, C free atoms) of AIBC, AICB. BAIC are discussed in detail.展开更多
The ionization energies （IEs） of cyclopropenylidene （c-C3H2）, propargylene （HCCCH） and propadienylidene （H2CCC） have been computed using the CCSD（T）/CBS method, which involves the approxixnation to the compl...The ionization energies （IEs） of cyclopropenylidene （c-C3H2）, propargylene （HCCCH） and propadienylidene （H2CCC） have been computed using the CCSD（T）/CBS method, which involves the approxixnation to the complete basis set （CBS） limit at the coupled cluster level with single and double excitations plus quasi-perturbative triple excitation effect （CCSD（T））. The zero-point vibrational energy correction, the core-valence electronic correction, the scalar relativistic effect and the high level correction beyond the CCSD（T） excitations have also been made in these calculations. The CCSD（T）/CBS values for the IN（c-C3H2） and IE（HCCCH） of 9.164, 8.987 eV are in good agreement with the experimental values of （9.15±0.03） and （8.96±0.04） eV. The CCSD（T）/CBS calculations yield the IE values of 10.477 and 10.388 eV for the ionization transitions H2CCC→H2CCC^＋ （^2A1, C2v） and H2CCC→H2CCC＋ （^2A＇, Cs）, respectively. On the basis of the Franek-Condon factor consideration, the IE of （10.43±0.02） eV determined in the previous single-photon ionization experiment most likely corresponds to the ionization threshold for the H2CCC→H2CCC^＋（^2A1, C2v） transition. Although the precision of the experimental IN measurements fpr c-C3H2, HCCCH, and H2CCC is insufficient to pin down the accuracy of the theoretical calculations to better than ±30 meV, the excellent agreement between the experimental and theoretical IE values observed in the present study indicates that the CCSD（T）/CBS calculations together with high-order correlation corrections are capable of yielding reliable IE predictions for simple hydrocarbon carbenes and bi-radicals. We have also reported the heats of formation at 0 K （△H^of0） and 298 K （△H^of298）for c-C3H2/c-C3H2^＋, HCCCH/HCCCH^＋, and H2CCC/H2CCC^＋, The available experimental △H^of0 and △H^of298 values for c-C3H2/c C3H2^＋, HCCCH/HCCCH^＋ are found to be in good accord with the CCSD（T）/CBS predictions after taking into account the experimental uncertainties.展开更多
文摘By uae of ab initio and analytic energy gradient method, twelve optimized electronic states of AICB,AIBC, BAIC in six geometric configurations are determined at all electron UHF(RHF) /6-31G level, their singles and doubles CI (CISD) energies are also obtained. The Stabillties for the atates of AICB have been investigated based on the vibrational analysis. binding energy and fragmentation energy. The ground state is 3∑+ of AICB (C∞. TAIC= 1.7497.,TBC=1.3511 A = 206.7, 799.5, 1802.9 cm-1, T=0), the second state is 1A' of AICB (Cs,TAIC=1.9162, TBC = 1.3154 A, ∠AICB=179。8307, =238.5, 575. 1,1767. 5.cm-1, T =2432.84 cm-1). The fragmentations of vallous States (fragmentation products are AIB,AIC, BC diatomic clusters. and Al, B, C free atoms) of AIBC, AICB. BAIC are discussed in detail.
文摘The ionization energies （IEs） of cyclopropenylidene （c-C3H2）, propargylene （HCCCH） and propadienylidene （H2CCC） have been computed using the CCSD（T）/CBS method, which involves the approxixnation to the complete basis set （CBS） limit at the coupled cluster level with single and double excitations plus quasi-perturbative triple excitation effect （CCSD（T））. The zero-point vibrational energy correction, the core-valence electronic correction, the scalar relativistic effect and the high level correction beyond the CCSD（T） excitations have also been made in these calculations. The CCSD（T）/CBS values for the IN（c-C3H2） and IE（HCCCH） of 9.164, 8.987 eV are in good agreement with the experimental values of （9.15±0.03） and （8.96±0.04） eV. The CCSD（T）/CBS calculations yield the IE values of 10.477 and 10.388 eV for the ionization transitions H2CCC→H2CCC^＋ （^2A1, C2v） and H2CCC→H2CCC＋ （^2A＇, Cs）, respectively. On the basis of the Franek-Condon factor consideration, the IE of （10.43±0.02） eV determined in the previous single-photon ionization experiment most likely corresponds to the ionization threshold for the H2CCC→H2CCC^＋（^2A1, C2v） transition. Although the precision of the experimental IN measurements fpr c-C3H2, HCCCH, and H2CCC is insufficient to pin down the accuracy of the theoretical calculations to better than ±30 meV, the excellent agreement between the experimental and theoretical IE values observed in the present study indicates that the CCSD（T）/CBS calculations together with high-order correlation corrections are capable of yielding reliable IE predictions for simple hydrocarbon carbenes and bi-radicals. We have also reported the heats of formation at 0 K （△H^of0） and 298 K （△H^of298）for c-C3H2/c-C3H2^＋, HCCCH/HCCCH^＋, and H2CCC/H2CCC^＋, The available experimental △H^of0 and △H^of298 values for c-C3H2/c C3H2^＋, HCCCH/HCCCH^＋ are found to be in good accord with the CCSD（T）/CBS predictions after taking into account the experimental uncertainties.
