Unravelling the Origin of Intermolecular Interactions Using Absolutely Localized Molecular Orbitals

Abstract

An energy decomposition analysis (EDA) method is proposed to isolate physically relevant components of the total intermolecular interaction energies such as the contribution from interacting frozen monomer densities, the energy lowering due to polarization of the densities, and the further energy lowering due to charge-transfer effects. This method is conceptually similar to existing EDA methods such as Morokuma analysis but includes several important new features. The first is a fully self-consistent treatment of the energy lowering due to polarization, which is evaluated by a self-consistent field calculation in which the molecular orbital coefficients are constrained to be block-diagonal (absolutely localized) in the interacting molecules to prohibit charge transfer. The second new feature is the ability to separate forward and back-donation in the charge-transfer energy term using a perturbative approximation starting from the optimized block-diagonal reference. The newly proposed EDA method is used to understand the fundamental aspects of intermolecular interactions such as the degree of covalency in the hydrogen bonding in water and the contributions of forward and back-donation in synergic bonding in metal complexes. Additionally, it is demonstrated that this method can be used to identify the factors controlling the interaction of the molecular hydrogen with open metal centers in potential hydrogen storage materials and the interaction of methane with rhenium complexes.

Microscopic properties of liquid water from combined ab initio molecular dynamics and energy decomposition studies

“…We conclude by noting that the development of secondgeneration CPMD 14 as well as ALMO EDA 45,173 are both for themselves important methodological achievements that had been instrumental to elucidate the water dimer and liquid water, respectively. Nevertheless, neither method alone but only the combination allowed for the additional insights to eventually reconcile the two existing and seemingly opposite models of liquid water -the traditional symmetric and the recently proposed asymmetric -and represent an important step towards a better understanding of the electronic structure of the HB network of one of the most important liquids on Earth.…”

“…In this review, we discuss a novel energy decomposition analysis scheme based on absolutely localized molecular orbitals (ALMO EDA) 45,46 . Unlike conventional MOs, which are generally delocalized over all molecules in the system, ALMOs are expanded in terms of the atomic orbitals of only a given molecule [47][48][49][50] .…”

“…Unlike conventional MOs, which are generally delocalized over all molecules in the system, ALMOs are expanded in terms of the atomic orbitals of only a given molecule [47][48][49][50] . Although ALMOs were originally used to speed up the calculation of SCF energies for large ensembles of molecules 50 , they are now widely used in energy decomposition analysis (EDA) [44][45][46] . It should be mentioned that since the introduction of ALMO EDA 45 , ALMO-based decomposition methods have been extended to many-determinant wave functions 51 .…”

Unprecedented high-temperature CO2 selectivity in N2-phobic nanoporous covalent organic polymers

“…The ab initio relative binding affinity for CO 2 versus N 2 (3-8 kJ mol À 1 ) is in reasonable agreement with the experimental relative heat of adsorption data for various azoCOPs (5-9 kJ mol À 1 ). Energy decomposition analysis 51 suggests that the frozen density repulsion as well as the lack of sufficient dispersion interactions between N 2 gas molecules and the azo groups are responsible for the moderate binding strength of N 2 /azo interaction compared with the stronger CO 2 /azo binding ( Supplementary Fig. S24).…”

Electronic structure theory to decipher the chemical bonding in actinide systems

“…These developments have taken place aiming to overcome limitations of the original schemes and provide more chemical significance to the energy components, which are not uniquely defined. We can cite, for example, CSOV (Constrained Space Orbital Variations) [107], RVS (Reduced Variational Space Self-Consistent-Field) [108], SAPT (Symmetry-Adapted Perturbation Theory) [109], NEDA (Natural Energy Decomposition Analysis) [110][111][112], LMOEDA (Localized Molecular Orbital Energy Decomposition Analysis) [113], ALMO-EDA (Absolutely Localized Molecular Orbital [114]), FMO (Fragment Molecular Orbital [115][116][117]) and a Morokuma-type EDA developed by Ziegler and Rauk [118][119][120]. Certainly, this list is not exhaustive, but recalls some popular currently used EDA schemes.…”