Collect. Czech. Chem. Commun. 2011, 76, 327-341
Published online 2011-03-23 23:02:39

Potential energy curve of N2 revisited

Vladimír Špirkoa,*, Xiangzhu Lib and Josef Paldusb

a Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i, Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
b Department of Applied Mathematics, University of Waterloo, Waterloo, ON Canada N2L 3G1


Recently generated ground state potential energy curves (PECs) for the nitrogen molecule, as obtained with the reduced multireference (RMR) coupled-cluster (CC) method with singles and doubles (RMR-CCSD), and its version corrected for the secondary triples RMR-CCSD(T), using cc-pVXZ basis sets with X = D, T, and Q, as well as the extrapolated complete basis set (cbs) limit (X. Li and J. Paldus: J. Chem. Phys. 2008, 129, 054104), are compared with both the highly accurate theoretical configuration interaction PEC of Gdanitz (Chem. Phys. Lett. 1998, 283, 253) and analytic PECs obtained by fitting an extensive set of experimental data (R. J. Le Roy et al.: J. Chem. Phys. 2006, 125, 164310). These results are analyzed using a morphing procedure based on the reduced potential curve (RPC) method of Jenč. It is found that an RPC fit of both theoretical potentials can be achieved with only a few parameters. The RMR PECs are found to provide an excellent description of experimentally available vibrational levels, but significantly deviate from those of Gdanitz’s PEC for highly stretched geometries, yet still do provide a qualitatively correct PECs that lie within the region delimited by Le Roy’s analytical PECs.

Keywords: Reduced multireference coupled-cluster method; Reduced potential curve method; Nitrogen molecule potential energy curves.

References: 46 live references.