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.

[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)
