Energy Decomposition Analysis
*****************************

In BAND there are two fragment-based energy decomposition methods
available: the periodic energy decomposition analysis (PEDA) [1] and
the periodic energy decomposition analysis combined with the natural
orbitals of chemical valency method (PEDA-NOCV) [1].


Periodic Energy Decomposition Analysis (PEDA)
=============================================

   PEDA Yes/No

"PEDA"
   Type:
      Bool

   Default value:
      No

   Description:
      If present in combination with the fragment block, the
      decomposition of the interaction energy between fragments is
      invoked.

If used in combination with the "fragment" keyblocks the decomposition
of the interaction energy between fragments is invoked and the
resulting energy terms (\Delta E_{int}, \Delta E_{disp}, \Delta
E_{Pauli}, \Delta E_{elstat}, \Delta E_{orb}) presented in the output
file. (See the example or the tutorial)

Attention:

  In case of the error message "Fragments cannot be assigned by a
  simple translation!", BAND does only allow for fragments which can
  be transformed to the structure in the PEDA calculation by a simple
  translation. So, a rotation is not allowed.


Periodic Energy Decomposition Analysis and natural orbitals of chemical valency (PEDA-NOCV)
===========================================================================================

"PEDANOCV (block-type)"

If present in combination with the "fragment" keyblocks and the "PEDA"
key the decomposition of the orbital relaxation term is performed. The
binary result file will contain the information to plot NOCV Orbitals
and NOCV deformation densities.

See also:

  * example

  * tutorial

  * advanced tutorial

   PEDANOCV
      EigvalThresh float
      Enabled Yes/No
   End

"PEDANOCV"
   Type:
      Block

   Description:
      Options for the decomposition of the orbital relaxation (pEDA).

   "EigvalThresh"
      Type:
         Float

      Default value:
         0.001

      GUI name:
         Use NOCVs with ev larger than

      Description:
         The threshold controls that for all NOCV deformation
         densities with NOCV eigenvalues larger than EigvalThresh the
         energy contribution will be calculated and the respective
         pEDA-NOCV results will be printed in the output

   "Enabled"
      Type:
         Bool

      Default value:
         No

      GUI name:
         Perform PEDA-NOCV analysis

      Description:
         If true in combination with the fragment blocks and the pEDA
         key, the decomposition of the orbital relaxation term is
         performed.

[1] M. Raupach and R. Tonner, *A periodic energy decomposition
    analysis method for the investigation of chemical bonding in
    extended systems*, The Journal of Chemical Physics 142, 194105
    (2015).
