Skip to main content
Theoretical Study of Vibronic Perturbations in Magnesium Carbide
Molecular Physics
  • Phalgun Lolur
  • Richard Dawes, Missouri University of Science and Technology
  • Michael C. Heaven
Understanding molecular systems with complex multi-configurational bonding has been of interest to both experimentalists and theoreticians for many years. High level dynamically weighted MRCI calculations were used to generate accurate potential energy curves for the triplet ground state 3Σ-, and triplet excited states up to (4 3Σ-, 4 3Πand 1 3Δ) and quintet (1 5Σ- and 1 5Π) states up to 50,000 cm-1 above the ground state minimum. The lowest four 3Πstates of magnesium mono-carbide (MgC) are strongly coupled leading to lifetimes that are shortened by pre-dissociation for most of the vibronic states. Non-adiabatic derivative couplings between the 3Πstates were used to determine diabatic potential energy curves. The state mixing role of spin-orbit coupling, which is much weaker than the non-adiabatic interactions, is discussed. A coupled vibronic Hamiltonian was solved to compute and assign strongly mixed vibronic states. The results are compared and contrasted with the valence iso-electronic beryllium carbide (BeC) system whose results were published earlier [B.J. Barker, I.O. Antonov, J.M. Merritt, V.E. Bondybey, M.C. Heaven, and R. Dawes, J. Chem. Phys. 137, 214313 (2012)]. Transitions, spectroscopic constants and band origins are expected to aid experimental detection of MgC in the future.
Research Center/Lab(s)
Center for High Performance Computing Research
Keywords and Phrases
  • Carbides,
  • Excited States,
  • Ground State,
  • Magnesium,
  • Molecular Physics,
  • Diabatisation,
  • Interstellar,
  • MRCI,
  • PEC,
  • Vibronic,
  • Potential Energy,
  • Dynamic-weighting
Document Type
Article - Journal
Document Version
File Type
© 2016 Taylor & Francis Ltd., All rights reserved.
Publication Date
Citation Information
Phalgun Lolur, Richard Dawes and Michael C. Heaven. "Theoretical Study of Vibronic Perturbations in Magnesium Carbide" Molecular Physics Vol. 114 Iss. 2 (2016) p. 162 - 171 ISSN: 0026-8976
Available at: