• DOI:10.1063/1.5097899
• Corpus ID: 90259604

Effective non-adiabatic Hamiltonians for the quantum nuclear motion over coupled electronic states.

@article{Mtyus2019EffectiveNH,
  title={Effective non-adiabatic Hamiltonians for the quantum nuclear motion over coupled electronic states.},
  author={Edit M{\'a}tyus and Stefan Teufel},
  journal={The Journal of chemical physics},
  year={2019},
  volume={151 1},
  pages={
          014113
        }
}

• E. Mátyus, S. Teufel
• Published 29 March 2019
• Physics
• The Journal of chemical physics

The quantum mechanical motion of the atomic nuclei is considered over a single- or a multidimensional subspace of electronic states which is separated by a gap from the rest of the electronic spectrum over the relevant range of nuclear configurations. The electron-nucleus Hamiltonian is block-diagonalized up to O(εn+1) through a unitary transformation of the electronic subspace, and the corresponding nth-order effective Hamiltonian is derived for the quantum nuclear motion. Explicit but general formulas are given for the second- and the third-order corrections. As a special case, the second-order Hamiltonian corresponding to an isolated electronic state is recovered which contains the coordinate-dependent mass-correction terms in the nuclear kinetic energy operator. For a multidimensional, explicitly coupled electronic band, the second-order Hamiltonian contains the usual Born-Oppenheimer terms and nonadiabatic corrections, but generalized mass-correction terms appear as well. These, earlier neglected terms, perturbatively account for the outlying (discrete and continuous) electronic states not included in the explicitly coupled electronic subspace.