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.