#!/bin/sh

# Application of the Ligand Field DFT approach for the calculation
# of the g-tensor. The g-tensor is only calculated for Kramer doublet states.
# This example calculates the g-tensor of the ground and excited doublet states
# of Co(acacen) with a Co d^7 electron configuration.

# First an average of configuration calculation (AOC) is performed, where 7
# electrons are equally distributed over the 5 orbitals that have the most
# dominant Co 3d character. Depending on the electron configuration this might
# be a non-trivial task. Here the Keeporbitals=0 and Freeze functionality is used,
# such that ADF will on successive SCF cycles assign electrons to the MOs
# that maximally resemble - in spatial form - those that were occupied in 0th
# (in fact 1st) cycle. Note that the orbitals that have the most
# dominant Co 3d character in the 1st cycle are orbitals 71, 72, 73, 74, and 75,
# whereas at the end of the SCF they are 71, 72, 73, 74, and 77.
# 
# Symmetry NOSYM should be specified.


SCM_LFDFT="$AMSHOME/examples/adf/Co_LFDFT/LFDFT"
export SCM_LFDFT

$AMSBIN/ams <<eor
System
  Atoms
   Co     0.000000    0.000000    0.000000
   N      1.327385    1.278147    0.000000
   N      1.327385   -1.278147    0.000000
   O     -1.395357    1.224920    0.000000
   O     -1.395357   -1.224920    0.000000
   C      2.704031    0.764453    0.000000
   C      2.704031   -0.764453    0.000000
   C     -1.309408    2.515386    0.000000
   C     -1.309408   -2.515386    0.000000
   C      1.166666    2.611094    0.000000
   C      1.166666   -2.611094    0.000000
   C     -0.103243   -3.216502    0.000000
   C     -0.103243    3.216502    0.000000
   H      3.246281   -1.139682    0.884137
   H      3.246281    1.139682    0.884137
   H      3.246281    1.139682   -0.884137
   H      3.246281   -1.139682   -0.884137
   C     -2.626185    3.259046    0.000000
   C     -2.626185   -3.259046    0.000000
   C      2.374732    3.518898    0.000000
   C      2.374732   -3.518898    0.000000
   H     -3.453721   -2.540862    0.000000
   H     -3.453721    2.540862    0.000000
   H     -0.145492    4.305797    0.000000
   H     -0.145492   -4.305797    0.000000
   H      3.008094    3.350507    0.884680
   H      3.008094   -3.350507    0.884680
   H      3.008094    3.350507   -0.884680
   H      3.008094   -3.350507   -0.884680
   H     -2.710536    3.904463    0.886944
   H     -2.710536   -3.904463    0.886944
   H     -2.710536    3.904463   -0.886944
   H     -2.710536   -3.904463   -0.886944
   H      2.061821   -4.568536    0.000000
   H      2.061821    4.568536    0.000000
  End
  Charge 0
End

task SinglePoint

Engine adf
  Symmetry NOSYM
  IrrepOccupations
   A 140 1.4 1.4 1.4 1.4 1.4 
  End
  Occupations Keeporbitals=0 Freeze
  basis
     Core None
     Type DZ
     PerAtomType Symbol=Co File=ZORA/TZP/Co
  End
  XC
    GGA PBE
  End
EndEngine
eor

# When the AOC calculation is ready, you need to make sure that indeed the
# partially occupied orbitals are dominantly d orbitals. In the ADF output you
# can find the character of the MOs in the list of all MOs, ordered by energy,
# with the most significant SFO gross populations.

# First the LFDFT calculation is performed without spin-orbit coupling (soc 0),
# in which pure spin states are calculated, doublets and quartets in this case.
# Next the LFDFT calculation is performed including spin-orbit coupling (soc 1),
# which is needed for the g-tensor calculation. In this case there is 1
# shell, and the nlval for 3d is '3 2'. The MO indices should be the
# fractionally occupied levels of the AOC calculation (in this case 71 72 73 74 77).

# One should be careful when interpreting the g-tensor for 2 Kramer doublets
# that are close in energy. In the effective Hamiltonian used to interpret ESR
# experiments, an effective spin=3/2 might be used.

$AMSBIN/lfdft << eor
 adffile ams.results/adf.rkf
 nshel 1
 nlval 3 2
 MOind 71 72 73 74 77
 soc 0.0
 DegeneracyThreshold 1.0E-5
eor

$AMSBIN/lfdft << eor
 adffile ams.results/adf.rkf
 nshel 1
 nlval 3 2
 MOind 71 72 73 74 77
 soc 1.0
 DegeneracyThreshold 1.0E-5
eor