Charges¶

Default Atomic Charge Analysis¶

By default BAND computes the following atomic charge analyses:

Hirshfeld Charges 1 2
Voronoi Deformation Charges (VDD, Voronoi Deformation Density)
Mulliken Charges (note: not calculated for Spin-Orbit calculations)
CM5 (Charge Model 5) 3 4

These atomic charges are printed to the output file and can be visualized using the AMSview GUI module.

A more detailed output of the atomic charges can be printed by specifying following print option (note: in Band 2017 and previous versions this detailed output was printed by default):

Print AtomicChargesDetails

Bader Analysis (AIM)¶

The QTAIM (Quantum Theory of Atoms in Molecules), also known as Bader Analysis can be enabled in the GridBasedAIM input block:

GridBasedAIM
   Enabled Yes/No
   Iterations integer
   SmallDensity float
   UseStartDensity Yes/No
End

GridBasedAIM

Type: Block
Description: Invoke the ultra fast grid based Bader analysis.

Enabled

Type: Bool
Default value: No
GUI name: Bader (AIM): Atomic properties
Description: Invoke the ultra fast grid based Bader analysis.

Iterations

Type: Integer
Default value: 40
Description: The maximum number of steps that may be taken to find the nuclear attractor for a grid point.

SmallDensity

Type: Float
Default value: 1e-06
Description: Value below which the density is ignored. This should not be chosen too small because it may lead to unassignable grid points.

UseStartDensity

Type: Bool
Default value: No
Description: Whether the analysis is performed on the startup density (True) or on the final density (False).

AIMCriticalPoints
   Enabled Yes/No
   EqvPointsTol float
   GridPadding float
   GridSpacing float
End

AIMCriticalPoints

Type: Block
Description: Compute the critical points of the density (Atoms In Molecules). The algorithm starts from a regular mesh of points, and from each of these it walks towards its corresponding critical point.

Enabled

Type: Bool
Default value: No
GUI name: : Critical points and bond paths
Description: Compute the critical points of the density (Atoms In Molecules). The algorithm starts from a regular mesh of points, and from each of these it walks towards its corresponding critical point.

EqvPointsTol

Type: Float
Default value: 0.27
Unit: Bohr
Description: If the distance between two critical points is smaller than this value, the two critical points are considered to be the same point.

GridPadding

Type: Float
Default value: 0.7
Unit: Bohr
Description: How much extra space is added to the starting guess domain in the search for the critical points

GridSpacing

Type: Float
Default value: 0.5
Unit: Bohr
Description: The distance between the initial trial points.

Note

The Bader (AIM) analysis is performed on the fitted density (see ZlmFit). We advise to use a Good (or better) ZlmFit quality.

References

1: F.L. Hirshfeld, Bonded-atom fragments for describing molecular charge densities, Theoretica Chimica Acta 44, 129 (1977)
2: K.B. Wiberg and P.R. Rablen, Comparison of atomic charges derived via different procedures, Journal of Computational Chemistry 14, 1504 (1993)
3: A.V. Marenich, S.V. Jerome, C.J. Cramer, D.G. Truhlar, Charge Model 5: An Extension of Hirshfeld Population Analysis for the Accurate Description of Molecular Interactions in Gaseous and Condensed Phases, Journal of Chemical Theory and Computation 8, 527 (2012)
4: C.A. Peeples and G. Schreckenbach, Implementation of the SM12 Solvation Model into ADF and Comparison with COSMO, Journal of Chemical Theory and Computation 12, 4033 (2016)