The Block‐Localized Wavefunction (BLW) Perspective of Chemical Bonding

Energy decomposition analysis

“…Depending on the preference of the author, he/she may prefer to use alternative methods. Here we mention the Block-Localized Wave function (BLW) EDA of Mo [16][17][18][19][20] and the Generalized Product Function (GPF) EDA by Nascimento, [21][22][23] which are based on Valence Bond (VB) theory. The BLW approach was later extended to DFT calculations.…”

Intramolecular multi-bond strain: the unrecognized side of the dichotomy of conjugated systems

“…1a . This has been the focal point for π conjugation, and ab initio valence bond (VB) methods, 29 – 32 , 51 including our block-localized wavefunction (BLW) 52 – 54 can evaluate the magnitude of this stabilizing effect. However, the interaction between occupied orbitals π A and π B cannot be neglected; this interaction is obviously repulsive and is usually termed steric repulsion ( Fig.…”

“…Here we compare the relative σ–σ and π–π repulsions with model systems of linear B 2 H 4 ( ref. 55–57 ) and B 4 H 2 at the B3LYP/6-311+G(d,p) level using the BLW method 52 – 54 which is the simplest variant of ab initio valence bond (VB) theory. The reason that we chose boron systems here is that the boron atom is electron-deficient and thus we can strictly keep its certain p orbitals unoccupied and examine the evolution of repulsive interactions with little interference, while importantly, the neutrality of these systems is maintained, e.g.…”

“…Linear B 4 H 2 (HB B–B BH) offers an interesting opportunity to directly probe the π–π repulsion with two localized π pairs that are either parallel or perpendicularly arranged. The ground state of linear B 4 H 2 has two 4-center-2-electron (Π24) bonds, and if we strictly localize each pair on two terminal B–B bonds with the BLW method, 52 – 54 we derive the localized state with two perpendicular π bonds (shown on the right side of Fig. 2b ).…”

A Critical Look at Linus Pauling’s Influence on the Understanding of Chemical Bonding

“…However, it is fair to say that problems like the homolytic bond breaking of electron-pair bonds are more easily dealt with using VB calculations, which remains an important approach in the toolbox of quantum chemical methods [ 99 , 100 , 101 , 102 , 103 , 104 , 126 , 127 ]. The VB and MO methods have been compared and discussed in several papers, which shed further light on the two approaches [ 128 , 129 , 130 , 131 , 132 , 133 , 134 ].…”