ewaldbackground
***************
Converges the self-consistent polarized background of a periodic system with Ewald summation
The following table contains the defaults input options for the calculator, The default `OPTIONAL` means this option is switched off, if no input is given. 
`REQUIRED` arguments have to be specified, otherwise an error is thrown.

.. list-table::
   :header-rows: 1
   :widths: 30 20 15 15
   :align: center

   * - Property Name
     - Default Value
     - Description
     - Valid Input
   * - multipoles
     - system.xml
     - MPS mapping file (xml) of the system
     - 
   * - output.checkpoint
     - ewaldbackground.hdf5
     - | HDF5 file for the converged background (used by qmmm Ewald
       | regions)
     - 
   * - coulombmethod.alpha
     - OPTIONAL
     - | Ewald splitting parameter; derived from the box and screening_factor
       | if not set
     - float+
   * - coulombmethod.k_max
     - OPTIONAL
     - | Reciprocal-space cutoff; derived from alpha and screening_factor
       | if not set
     - float+
   * - coulombmethod.shape
     - cube
     - | Shape of the macroscopic sample (surface term): cube or
       | sphere (same term), or slab
     - | cube
       | sphere
       | slab
   * - realspace.r_min
     - 1.0
     - | Real-space sum over periodic images: minimal shell radius
       | before convergence may be declared
     - float+
   * - realspace.field_tol
     - 1e-8
     - | Real-space sum: convergence threshold on the field contribution
       | of one shell (atomic units)
     - float+
   * - realspace.screening_factor
     - 6.0
     - | Accuracy of the Ewald sums (dimensionless): sets the real-space
       | cutoff screening_factor/alpha and a reciprocal cutoff
       | with the same error (erfc(screening_factor)); lower it
       | only deliberately
     - float+
   * - polarmethod.thole_a
     - 0.39
     - Thole damping parameter
     - float+
   * - polarmethod.induce
     - true
     - Compute induced dipoles (false: static multipoles only)
     - bool
   * - polarmethod.max_iter
     - 200
     - Maximal number of iterations of the induction solver
     - int+
   * - polarmethod.tolerance
     - 1e-8
     - Convergence tolerance of the induction solver
     - float+
   * - polarmethod.use_jor
     - false
     - | Use Jacobi over-relaxation (as the legacy code) instead
       | of preconditioned conjugate gradients
     - bool
   * - polarmethod.jor_omega
     - 0.35
     - Relaxation parameter for use_jor
     - float+
   * - polarmethod.use_block_jacobi_preconditioner
     - false
     - | Block-Jacobi (per segment) preconditioner for the conjugate
       | gradient solver
     - bool
   * - polarmethod.debug_match_legacy_first_step
     - false
     - | Debugging: replicate the two-phase first step of the legacy
       | code
     - bool
.. note::
   An *xml* file containing the defaults for the `ewaldbackground` calculator can be created via `-p ewaldbackground -o FILENAME` command line options `