#! /bin/sh

# eigenvalue-only self-consistent GW calculation for Water.

# We change here several options in the GW block to illustrate how this works 

# We chose M06-2X as starting point 
# We chose good numerical quality. This implies that 20 imaginary time and frequency points each are used 

# nStates 3
# ==> We want to print out the 3 highest occupied, and the 3 lowest unoccupied quasi-particle states

# nDIIS 5
# ==> We use DIIS to converge the quasi-particle energies (linear mixing is possible as well, but it is not recommended)
# ==> Per default, the DIIS algorithm in evGW considers the last 10 iterations. We only want 5 here. If for some reason
# ==> your evGW calculation should not converge, this is the first parameter to look into 

# Converge HOMO=5e-3 
# ==> We consider the procedure to be converged when the HOMO quasi-particle energy between 2 iterations does not change
# ==> by more than 5 meV


$AMSBIN/ams << eor
Symmetry
  SymmetrizeTolerance 0.001
End

System
  Atoms
    O  0.0000 0.0000 0.0000
    H  0.7571 0.0000 0.5861
    H -0.7571 0.0000 0.5861
  End
  Symmetrize Yes
End

task SinglePoint

Engine adf
  Basis
    Core None
    Type TZ2P
  End
  XC
     libxc M06-2X
  end
  MBPT
     nTime 20
     nFrequency 20
  End  
  numericalQuality Good

  GW
     DIIS 5 
     nStates 3
     Converge HOMO=5e-3
     selfconsistency evGW
  END

EndEngine
eor