The Block-Localized Wavefunction (BLW) Method and Its Applications

The block-localized wavefunction (BLW) method is the simplest ab initio variant of valence bond (VB) theory. It can derive the self-consistent wavefunction for a strictly electron-localized state, which can be a Lewis or resonance structure in the traditional resonance-theoretic language, or a generalized hypothetical non-charge transferred state based on the specific research question to be addressed. By comparing the computational results from regular MO or DFT methods at the same theoretical level, the BLW method allows the quantification of the energetic, geometrical, and spectral impacts of intra- and intermolecular electron transfer processes and reactions. In this article, we introduced the essences of the BLW method and showcased how this method can be applied to the elucidation of non-covalent interactions with the examples of halogen bonding, and binding and activation mechanisms of small molecules such as CO, N2 and CO2 by main group catalysts.