Molcas Forum

toni

Member

Registered: 2022-10-05

Posts: 2

Oscillator strengths for core excitations

Hi all,
I want to compute X-ray absorption spectra at the sulfur K-edge for various organic molecules containing one or two sulfur atoms. So far I computed the transition energies by rotating the two S(1s) orbitals into RAS1 and forcing one hole in RAS1 using hexs command. I then computed the ground state where I deleted the hexs command to get the transition energies, so I actually ran two separate calculations (example input file can be found below).
Now, I also want to know the corresponding dipole oscillator strength etc using RASSI but I'm not sure if it works when having two separate calculations for the transition energies. Does anyone know if it's possible and if so, how to do it?
Many thanks in advance,
Toni 

&gateway
Coord
  10
DMDS  coordinates  in  Angstrom
S           -0.457537    0.914029   -0.506100
S            0.457537   -0.914029   -0.506100
C           -0.457537   -1.760964    0.813524
H           -1.513870   -1.782058    0.555233
H           -0.079436   -2.776020    0.911996
H           -0.304905   -1.227903    1.749230
C            0.457537    1.760964    0.813524
H            1.513870    1.782058    0.555233
H            0.079436    2.776020    0.911996
H            0.304905    1.227903    1.749230
Basis=aug-cc-pvdz
Group=Nosym
&SEWARD
&RASSCF
  Spin     =  1
  nactel   =  14  1  0
  inactive =  18
  alter    =  2; 1 1 19; 1 2 20
  supsym   =  1; 2 1 2
  ras1     =  2
  hexs     =  1; 1
  ras2     =  10
  CIRoot   =  10 10 1

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,011

Re: Oscillator strengths for core excitations

It is possible, although I believe the active spaces should be the same in numbers of orbitals and electrons and of similar enough shape. You just copy the JobIph files as JOBXXX and use the NrOfJobIph keyword, for example:

&RASSCF
...
CIRoot = 1 1 1

>COPY $Project.JobIph JOB001

&RASSCF
...
CIRoot = 10 10 1

>COPY $Project.JobIph JOB002

&RASSI
NrOfJobIph = 2 1 10
  1
  1 2 3 4 5 6 7 8 9 10

toni

Member

Registered: 2022-10-05

Posts: 2

Re: Oscillator strengths for core excitations

Great, thank you!