Abinitio Study On Molecular Geometry And Ro-vibrational Spectrum Of CO,OH^- And CO₂

Accurate potential energy function can completely describe geometric characteristics,force constants and spectrum constants can be obtained by parse the potential energy function.With the development of science and technology,molecular spectrum are widely used at many hot fields.Therefore,it put forward higher requirements for high temperature spectrum.Based on the analysis above,the paper study potential energy function and molecular spectrum by abinitio method.Second,theoretical study for the ground state of OH^-ion.Potential energy and dipole moment are obtained by the MRCI plus Davidson correction（MRCI+Q）with basis set of O=aug-cc-pV5 Z,H=cc-pV5 Z.9 vibrational states（J=0）are obtained by numerically solving the radical Schr?dinger equation of nuclear motion.The vibrational level,inertial rotation and centrifugal distortion constants are obtained for each state.Therefore,rotational levels and transition wavenumbers of 1-0 band are calculated.Spectrum constants are obtained which accord well with the experimental values.Third,theoretical study for the gound state of CO₂ molecule.Many methods are used for optimization of carbon dioxide molecule.Result show that resonance frequency,equilibrium internuclear distance and zero-point vibrational energy are excellent with experimental values at the casscf with basis set of O=aug-cc-pVTZ,H=cc-PVQZ.Based on it,a few of orbital energy of CO₂ are calculated which accord well with the reference.Potential energy are calculated by casscf/（O=aug-cc-pVTZ,H=cc-pVQZ）.Finally,some potential energy are fitted.Finally,calculation of the high-temperature spectrum for the CO,CO₂ molecule.Based on the calculation of partition function,line intensity of 1-0 band of CO and 01101-0001 band of CO₂ molecule have been calculated at medium temperature,high temperature,result show that line intensity are excellent with date at HITRAN.Therefore,line intensity of CO,CO₂ have been obtained by formula of line intensity at 4000 K,5000K.