Block-Localized Wavefunction (BLW) Method and Its Applications in Intramolecular and Intermolecular Interactions
Year: 2026
Type: article
Abstract: A key research objective in computational chemistry is to elucidate the nature of intramolecular and intermolecular interactions, which are the driving forces determining molecular properties and reactivity. In this respect, valence bond (VB) theory exhibits unique characteristics compared to molecular orbital (MO) theory, as it employs a bottom-up approach, expressing the molecular state wave function in terms of localized resonance structures composed of atomic orbitals. The block-localized wavefunction (BLW) method combines the advantages of both MO and VB theories and can be regarded as the simplest ab initio VB method with the efficiency of MO methods. It defines the wavefunction for an electron-localized (diabatic) state by partitioning the system into several physical blocks and constructing orbitals within only one of these blocks. While orbitals within the same block are constrained to be orthogonal, orbitals from different blocks are generally nonorthogonal. Thus, the BLW method can critically evaluate the impacts of electron transfer on molecular geometry, energy, and spectral properties. Furthermore, the energy decomposition approach based on the BLW method, or BLW-ED, can decompose intermolecular interactions into a series of physically meaningful energy components, including frozen, polarization, and charge-transfer energy terms. In this mini review, we showcase applications of the BLW method to selected intramolecular and intermolecular interactions, including resonance-assisted or inhibited hydrogen bonds, the anomeric effect, and red- and blue-shifted hydrogen and halogen bonds. In the end, we also briefly introduce our recently proposed "in situ" orbital correlations based on the BLW method.
Authors: Changwei Wang, Yirong Mo
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7162009709