Nuclear-Electronic Orbital (NEO) Methods

NEO methods enable description of nuclear quantum effects such as zero-point energy, proton delocalization, anharmonicity, and vibronic excitations with molecular orbital and density functional theory approaches. Q-Chem offers:

  • State-of-the-art parallel implementation to include nuclear quantum effects of specified hydrogen nuclei at low cost;

  • NEO methods for ground state properties:

    • NEO-HF and NEO-DFT with epc17-2 (LDA) and epc19 (GGA) electron-proton correlation functionals;

    • NEO-HF and NEO-DFT geometry optimizations.

  • NEO methods for electronic, vibrational, and vibronic excitation energies:

    • NEO-CIS and NEO-TDHF;

    • NEO-TDA and NEO-TDDFT.