Computational study of the ro-vibrational spectrum of CO–CO2

Abstract

An accurate ab initio ground-state intermolecular potential energy surface (PES) was determined for the CO-CO 2 Van der Waals dimer. The Lanczos algorithm was used to compute ro-vibrational energies on this PES. For both the C-in and the O-in T-shaped isomers, the fundamental transition frequencies agree well with previous experimental results. We confirm that the in-plane states previously observed are geared states. In addition, we have computed and assigned many other vibrational states. The rotational constants we determine from J = 1 energy levels agree well with their experimental counterparts. Planar and out-ofplane cuts of some of the wavefunctions we compute are quite different, indicating strong coupling between the bend and torsional modes. Because the stable isomers are T-shaped, vibration along the out-of-plane coordinates is very floppy. In CO-CO 2 , when the molecule is out-of-plane, interconversion of the isomers is possible, but the barrier height is higher than the in-plane geared barrier height.

Weakly-bound clusters of atmospheric molecules: infrared spectra and structural calculations of (CO2)n–(CO)m–(N2)p, (n,m,p) = (2,1,0), (2,0,1), (1,2,0), (1,0,2), (1,1,1), (1,3,0), (1,0,3), (1,2,1), (1,1,2)

“…There have been a number of theoretical studies of the CO 2 -CO interaction, 14,15 including two recent high level ab initio determinations of a four-dimensional potential surface. 16,17 In the case of CO 2 -N 2 , similar calculations have been reported at various levels of ab initio theory, most recently including a four-dimensional surface at the CCSD(T)-F12 triple zeta level. [18][19][20] Of course the structures of the present clusters also depend on the CO 2 -CO 2 , CO-CO, N 2 -N 2 , and CO-N 2 interaction potentials, which themselves have been extensively studied.…”

Collisional excitation of interstellar PN by H2: New interaction potential and scattering calculations

“…As we have done in the past for other van der Waals (vdW) linear dimers, [27][28][29][30][31][32][33][34][35][36] the 4D PES analytical representation was constructed using an automated interpolating moving leastsquares methodology, which has been recently released as a software package under the name AUTOSURF. 37 As usual, 38 a local fit was expanded about each data point, and the final potential is obtained as the normalized weighted sum of the local fits.…”

Fully quantum calculations of O2–N2 scattering using a new potential energy surface: Collisional perturbations of the oxygen 118 GHz fine structure line

“…As we have done in the past for other van der Waals dimers composed of linear monomer fragments, [74][75][76][77][78][79][80][81][82][83][84][85] an analytical representation of the PES was constructed using an automated interpolating moving least squares (IMLS) methodology, which is available as a software package under the name autosurf. 86 As usual, 87,88 a local fit was expanded about each data point, and the final potential is obtained as the normalized weighted sum of the local fits.…”