CO分子振转光谱的理论研究

采用从头算的多参考组态相互作用(MRCI)方法并结合基组aug-cc-pCVQZ计算了CO分子基态(X1Σ+)的势能曲线和偶极矩曲线，得到的势能曲线、偶极矩曲线分别与RKR势、文献的偶极矩曲线吻合较好。利用所得的势能，求解双原子分子核运动的Schrdinger方程找到了CO分子X1Σ+态转动量子数J=0时的70个振动态，对于每一振动态，分别计算了其振动能级G(v)、转动惯性常数B_v和离心畸变常数D_v，并把计算结果与已知的42个实验值做了详细比较，结果表明，计算的振动能级G(v)、转动惯性常数B_v、离心畸变常数D_v与实验值符合较好。利用G(v)，B_v导出的光谱常数谐振频率ω_e(2 160.1 cm-1)、非谐振频率ω_eχ_e(13.1 cm-1)、转动常数B_e(1.918 cm-1)、振转耦合常数α_e(0.017 3 cm-1)]也与实验值的光谱常数ω_e(2 169.8 cm-1)，ω_eχ_e(13.3 cm-1)，B_e(1.931 cm-1)，α_e(0.017 5 cm-1)]较为符合，这在一定程度上证明了方法MRCI/Aug-cc-pCVQZ对CO分子基态性质的计算是合适而可靠的。利用乘积近似方法计算了CO分子在常温、中温、高温时的配分函数，在此基础上，计算了CO分子在T=296 K时的1-0跃迁带的谱线强度，通过比较发现，计算所得的线强度与HITRAN数据库符合较好。进一步计算的CO分子X1Σ+态1-0，2-0，3-0，4-0，2-1，3-1和4-1跃迁带的带强度也与实验值较为吻合，同时首次计算了CO分子X1Σ+态3-2跃迁带、4-2跃迁带的线强度及带强度。

Theoretical Study of Ro-Vibrational Spectrum of CO Molecule

The potential energy curve (PEC) and dipole moment curve (DMC) for the ground state (X1Σ+) of CO molecule have been computed using the multi-reference configuration interaction (MRCI) method with aug-cc-pCVQZ basis sets. Results showed that the calculated PEC, DMC are in accord with RKR, reference, respectively. With the potential energy obtained at the MRCI/aug-cc-pCVQZ level of theory, 70 vibrational states (J=0) of the ground state of CO molecule are obtained by numerically solving the radical Schrdinger equation of nuclear motion. For each vibrational state, the vibrational energy levels G(v), the inertial rotation constants B_v and the centrifugal distortion constants D_v are reported, which accord well with the experimental values. The inertial rotation constants B_v, vibrational energy levels G(v) were fitted to determine spectroscopy constants, which the rotation coupling constant ω_e(2 160.1 cm-1), the anharmonic constant ω_eχ_e(13.3 cm-1), the equilibrium rotation constant B_e(1.931 cm-1) and the vibration-rotation coupling constant α_e(0.017 5 cm-1) are in good agreement with the experiment data ω_e(2 169.8 cm-1), ω_eχ_e(13.3 cm-1), B_e(1.931 cm-1), α_e(0.017 5 cm-1)], it is evident that MRCI/Aug-cc-pCVQZ is reliable for the calculation for the ground state of CO molecule. The line intensity of 1-0 transition band for the ground state of CO molecule is calculated by directly calculating the partition function at 296 K, the agreement between the calculated line intensity data and the data in HITRAN database is fairly good at 296 K. Band intensities of 1-0，2-0，3-0，4-0，2-1，3-1，4-1 bands are calculated for the ground state of CO molecule, which are in better agreement with the experimental values. Therefore, the line intensities and band intensities of 3-2 transition band, 4-2 transition band are firstly calculated.