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New CO-CO interaction potential tested by rovibrational calculations.
G W M Vissers1, A Hesselmann, G Jansen
1Institute of Theoretical Chemistry, NSRIM, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands.
The Journal of Chemical Physics
|March 3, 2005
Summary
This study calculates a potential energy surface for the carbon monoxide (CO) dimer using density functional theory and symmetry adapted perturbation theory. A combination of this and another method accurately predicts experimental data for CO dimers.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Spectroscopy
Background:
- Accurate potential energy surfaces (PES) are crucial for understanding molecular interactions and predicting spectroscopic properties.
- The carbon monoxide (CO) dimer is a fundamental system for studying intermolecular forces.
- Previous calculations using high-level coupled cluster methods provided a benchmark, but computational cost is high.
Purpose of the Study:
- To develop a reliable and computationally efficient four-dimensional potential energy surface (PES) for the rigid CO dimer.
- To investigate the accuracy of a combined density functional theory-symmetry adapted perturbation theory (DFT-SAPT) approach for describing the CO dimer interaction.
- To refine the PES by incorporating experimental data for improved agreement with observed rovibrational spectra.
Main Methods:
- Calculation of a four-dimensional PES for the CO dimer using a hybrid DFT-SAPT scheme.
- Fitting the calculated PES to analytic functions for efficient use in dynamical calculations.
- Computation of rovibrational energy levels using the fitted PES and comparison with experimental data.
Main Results:
- The DFT-SAPT PES demonstrates quality comparable to a previously computed coupled cluster single double and perturbative triples [CCSD(T)] surface.
- A weighted average of the DFT-SAPT and CCSD(T) potentials yields excellent agreement with experimental data for both ((12)CO)(2) and ((13)CO)(2) isotopologues.
- The optimal weighting was determined by matching the calculated energy gap between the lowest rotational stacks to experimental values.
Conclusions:
- The combined DFT-SAPT and CCSD(T) approach provides a highly accurate and potentially more accessible method for generating PES for molecular dimers.
- The refined PES accurately reproduces experimental rovibrational spectra, validating its quality for spectroscopic predictions.
- This work offers a valuable computational tool for further studies of the CO dimer and related systems.