What sort of SCF calculations are supported with external fields?

Questions
#1

Which types of SCF are supported with the $multipole_field section? I am particularly interested in ROKS calculations. A simple test:

$comment
  Ground state calculation.
$end

$molecule
  0   1
  O   0.0000000  0.0000000  0.1173000
  H   0.0000000  0.7572000 -0.4692000
  H   0.0000000 -0.7572000 -0.4692000
$end

$rem
  METHOD          PBE
  BASIS           pcseg-1
  MEM_TOTAL       8000
  MEM_STATIC      100
  SCF_CONVERGENCE 8
  SYMMETRY        FALSE
  SYM_IGNORE      TRUE
  THRESH          14
$end

@@@

$comment
  ROKS calculation on water - without field
$end

$molecule
  read
$end

$rem
  ROKS            TRUE
  METHOD          PBE
  BASIS           pcseg-1
  MEM_TOTAL       8000
  MEM_STATIC      100
  SCF_CONVERGENCE 8
  SCF_GUESS       READ
  SYMMETRY        FALSE
  SYM_IGNORE      TRUE
  THRESH          14
$end

@@@

$comment
  ROKS calculation on water - with field
$end

$molecule
  read
$end

$rem
  ROKS            TRUE
  METHOD          PBE
  BASIS           pcseg-1
  MEM_TOTAL       8000
  MEM_STATIC      100
  SCF_CONVERGENCE 8
  SCF_GUESS       READ
  SYMMETRY        FALSE
  SYM_IGNORE      TRUE
  THRESH          14
$end

$multipole_field
  z 0.0001
$end

runs and indeed produces a Stark shift in the excited state energy. I ran a more complex example:

$comment
  Ground state calculation on water.
$end

$molecule
  0   1
  O   0.0000000  0.0000000  0.1173000
  H   0.0000000  0.7572000 -0.4692000
  H   0.0000000 -0.7572000 -0.4692000
$end

$rem
  METHOD          SCAN
  BASIS           GEN
  PURECART        11
  MEM_TOTAL       8000
  MEM_STATIC      100
  SCF_CONVERGENCE 8
  SYMMETRY        FALSE
  SYM_IGNORE      TRUE
  THRESH          14
$end

$basis
H     0
aug-pcseg-2
****
O     0
aug-pcx-2
****
$end

@@@ 

$comment
  ROKS calculation on 1s -> 3s excited state of water - no field
$end

$molecule
  read
$end

$rem
  DELTA_SCF       TRUE  
  METHOD          SCAN
  BASIS           GEN
  PURECART        11
  MEM_TOTAL       8000
  MEM_STATIC      100
  SCF_CONVERGENCE 8
  SCF_GUESS       READ
  SYMMETRY        FALSE
  SYM_IGNORE      TRUE
  THRESH          14
$end

$delta_scf
  SOMO_1 1
  singlet restricted
  singlet_SCF_algorithm SGM
  singlet_SOMO_print    alpha
$end

$plots
  grid_spacing 0.35
  grid_range   5.0
$end

$basis
H     0
aug-pcseg-2
****
O     0
aug-pcx-2
****
$end

@@@ 

$comment
  ROKS calculation on 1s -> 3s excited state of water - with field (6e-2)
$end

$molecule
  read
$end

$rem
  DELTA_SCF       TRUE  
  METHOD          SCAN
  BASIS           GEN
  PURECART        11
  MEM_TOTAL       8000
  MEM_STATIC      100
  SCF_CONVERGENCE 8
  SCF_GUESS       READ
  SYMMETRY        FALSE
  SYM_IGNORE      TRUE
  THRESH          14
$end

$delta_scf
  SOMO_1 1
  singlet_SCF_algorithm SGM
  singlet restricted
$end

$basis
H     0
aug-pcseg-2
****
O     0
aug-pcx-2
****
$end

$multipole_field
  z 0.06
$end

@@@ 

$comment
  ROKS calculation on 1s -> 3s excited state of water - with field (-6e-2)
$end

$molecule
  read
$end

$rem
  DELTA_SCF       TRUE  
  METHOD          SCAN
  BASIS           GEN
  PURECART        11
  MEM_TOTAL       8000
  MEM_STATIC      100
  SCF_CONVERGENCE 8
  SCF_GUESS       READ
  SYMMETRY        FALSE
  SYM_IGNORE      TRUE
  THRESH          14
$end

$delta_scf
  SOMO_1 1
  singlet_SCF_algorithm SGM
  singlet restricted
$end

$basis
H     0
aug-pcseg-2
****
O     0
aug-pcx-2
****
$end

$multipole_field
  z -0.06
$end

and the results seem to agree well with Fig 4. of https://doi.org/10.1021/acs.jpca.2c08311, so I am tempted to conclude that the calculation works. However, wanted to verify with you to be certain, as there is no information in the manual about this.