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