Example: Multiresolution
************************

"Download Multiresolution_H2O.run"

   #! /bin/sh

   # This example demonstrates how to use different levels of numerical precision
   # for different regions, with the aim of increasing computational efficiency.

   # Let us assume that we are interested in having an accurate description only
   # for a subregion of a large chemical system (in this simple example, the
   # central water molecule). The system can be divided into sub-regions and
   # different levels of numerical accuracy can be used for each of these sub-
   # regions.

   # In this example we will tweak:
   # - the basis set (Basis)
   # - the numerical integration (BeckeGrid)
   # - the density fitting for Coulomb potential (ZlmFit)
   # - the fit-set used in the Hartree-Fock Resolution of identity (RIHartreeFock)

   # Note: For the regions for which no quality has been explicitly defined
   # through a QualityPerRegion keyword, the quality defined in NumericalQuality
   # will be used (Normal, in this example).

   $AMSBIN/ams <<eor

   Task SinglePoint

   System
     Atoms
        O    0.00000000       0.00000000       0.00000000    region=Accurate
        H    0.40399229      -0.65578342       0.63241539    region=Accurate
        H    0.81410032       0.55624569      -0.23129097    region=Accurate
        O   -3.02535626      -0.08473104      -0.47678489
        H   -2.56531481       0.62644005       0.07759386
        H   -2.25289644      -0.61700366      -0.80790649
        O    2.95394790      -0.54939973      -0.38206034
        H    3.91427727      -0.21304908      -0.44738291
        H    2.87780992      -1.13241278      -1.20853726
        O   -5.95425742      -0.56764616      -0.02016682    region=Far
        H   -5.26308282      -0.46969096       0.69255963    region=Far
        H   -5.42117992      -0.54361203      -0.86443121    region=Far
        O    6.25171470      -0.62004899      -0.03702467    region=Far
        H    6.16508647      -1.38696453       0.58541903    region=Far
        H    7.09161199      -0.16700550       0.23679419    region=Far
     End
   End

   Engine Band

      XC
         LibXC B3LYP
      End

      ! ========================================================
      ! Set different basis sets for atoms in different regions:
      ! ========================================================

      Basis
         Type DZ
         Core None
         PerRegion Region=Accurate Type=TZP
         PerRegion Region=Far      Type=SZ
      End

      ! =============================================================
      ! Set the NumerialQuality to be used for the atoms that are not
      ! explicitly defined through a QualityPerRegion keyword
      ! =============================================================

      NumericalQuality Normal

      ! ======================
      ! Numerical integration:
      ! ======================

      BeckeGrid
         QualityPerRegion Region=Accurate Quality=Good
         QualityPerRegion Region=Far      Quality=Basic
      End

      ! ======================================
      ! Density fitting for Coulomb potential:
      ! ======================================

      ZlmFit
         QualityPerRegion Region=Accurate Quality=Good
         QualityPerRegion Region=Far      Quality=Basic
      End

      ! ============================================================
      ! Hartree-Fock Resolution of identity (for hybrid functionals)
      ! ============================================================

      RIHartreeFock
         QualityPerRegion Region=Accurate Quality=Good
         QualityPerRegion Region=Far      Quality=Basic
      End

      Relativity Level=None

   EndEngine

   eor
