Analyzing the Effect of Charge Transfer Using Absolutely Localized Molecular Orbitals

  • Charge transfer (CT) in ALMO-EDA: stabilization effect due to inter-fragment orbital relaxation;

  • Perturbative charge-transfer analysis (CTA): decomposition of the amount of CT (\(\Delta\)Q) and the associated energetic stabilization (\(\Delta\)E) into forward and backward contributions;

  • Complementary occupied/virtual pairs (COVP) analysis:

    • Based on perturbative CTA;

    • Rotates the polarized ALMOs within a molecule to achieve a compact orbital representation of CT between a pair of molecules;

    • Helps chemists quantify and visualize CT effects.

  • Variational forward-backward (VFB) analysis:

    • Decomposes CT stabilization energy into forward and backward contributions using two variationally optimized "one-way" CT states;

    • Can be seamlessly integrated with the adiabatic ALMO-EDA scheme, facilitating analysis of the effects of forward and backward CT on molecular properties.