Chemical Bonding Analysis

The DFT codes ADF and BAND come with various analysis tools offering a detailed insight in the nature of individual chemical bonds and properties like charges, electron densities and potentials. With the integrated GUI these analysis options can be readily accessed and the analysis results are easily visualized in a clear and concise fashion.

The energy decomposition analysis (EDA) or extended transition state (ETS) analysis1 in ADF are powerful methods to dissect the interactions that constitute a chemical bond between fragments in a molecule:

∆Ebond =  ∆Estrain + ∆Eint

∆Eint = ∆Velstat  + ∆EPauli + ∆Eoi  +  ∆Edisp 

The total bonding consists of the interaction energy ∆Eint between the fragments and ∆Estrain, the strain or preparation energy involved in deforming the fragments to the geometries in the pro-molecule.

The interaction energy is further decomposed in terms which are more akin to standard concepts of chemistry. The electrostatic attraction ∆Velstat and Pauli repulsion ∆EPauli are sometimes conveniently summed together into a steric repulsion term.2
The stabilizing orbital interactions ∆Eoi describe the orbital mixing and charge transfer between the fragments when they form the molecule. In a symmetric molecule, these can be further decomposed into individual irreducible representations of the corresponding point group symmetry. Alternatively, an ETS-NOCV analysis3 decomposes the bonding interactions in the context of natural orbitals for chemical valence (NOCV).

1 T. Ziegler & A. Rauk, Theoret. Chim. Acta 45, 1-10 (1977).
2 F. M. Bickelhaupt & E. J. Baerends, In: Reviews in Computational Chemistry Vol. 15; K. B. Lipkowitz, D. B. Boyd, Eds. (2000)
3 M. Mitoraj & A. Michalak, J Mol Model. 13, 2 (2007)

Key features and benefits:

  • Easy visualization and analysis in integrated GUI: orbitals, densities, tensors, cut planes
  • Orbital-level interaction diagrams
  • Partial, local and total densities of states (DOS), Crystal Orbital Overlap Population (COOP)
  • Band structure analysis
  • Bond energy decomposition analysis (EDA), fragment-based approach
  • Periodic EDA: molecules interacting with nanotubes, surfaces and porous materials
  • ETS-NOCV: combined charge / bond energy analysis
  • Advanced charge density analysis: Voronoi, Hirshfeld, MDC, CM5, various bond orders, NBO, QT-AIM, IQA, NCI, SEDD, DORI, Fukui functions, Aromaticity indices
  • Efficient use of symmetry
  • Transfer integrals (for charge mobility)
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