Extended Symmetry-Adapted Perturbation Theory (XSAPT)

  • Benchmark-quality intermolecular interaction energies;

  • Energy decomposition analysis provides a powerful interpretive utility;

  • Unfolds interaction energies into contributions from electrostatics, Pauli repulsion, polarization, and London dispersion;

  • A fully many-body interaction energy protocol:

    • Accounts for many-body polarization effects via charge embedding;

    • Includes many-body dispersion interactions (MBD+esDQ potential).

  • Cost scales with monomer size; no need for supersystem calculations;

  • Faster than supersystem DFT for the DNA complex shown above (4,651 basis functions);

  • Trivially parallelizable across fragments;

  • Capable of high-accuracy interaction energies in systems larger than 10,000 basis functions.