Molcas Forum

karney

Member

From: University of San Francisco

Registered: 2018-09-07

Posts: 4

Website

CASSCF spin densities for Luscus visualization

Hello,
I am running CASSCF and CASPT2 calculations, and I would like to visualize the resulting CASSCF spin densities with Luscus. I used GRID_IT and created a .lus file, but I do not see how to obtain spin densities in Luscus. Is there some special information I have to supply to the GRID_IT command to generate readable spin densities in the .lus file? Any help would be greatly appreciated.

William Karney

---

William Karney
Prof. of Chemistry and Environmental Science
University of San Francisco

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,123

Re: CASSCF spin densities for Luscus visualization

You can probably use the *SpdOrb files with GRID_IT. But I'd recommend you to use .h5 files with Pegamoid instead: https://pypi.org/project/Pegamoid/

karney

Member

From: University of San Francisco

Registered: 2018-09-07

Posts: 4

Website

Re: CASSCF spin densities for Luscus visualization

Thanks for the reply Ignacio. I should have given more info in my initial post. I am using Molcas 8.2/8.4, not OpenMolcas, so I am not generating .h5 files. I have tried using GRID_IT with the SpdOrb.1 file that is produced, but I'm not sure I am doing it correctly. I have a separate GRID_IT command for each orbital symmetry in the active space. But I still do not understand how to get a summary plot of the alpha spin density and the beta spin density. Here is my input, for a C2v-symmetric molecule, with a 1A2 electronic state:
---------------

 &GATEWAY
Title
 Singlet 4-Nitrenylpyridine oxide,C2v,1A2,CASPT2/(10,9)/def2-TZVP//CASSCF(10,9)/def2-TZVP Energy
Symmetry
 x y
Basis Set
C.def2-TZVP....
C1    0.00000000     0.00000000    -1.50542691 Angstrom
C2    0.00000000     1.24497749    -0.72287426 Angstrom
C4    0.00000000     1.20604431     0.61606503 Angstrom
End of Basis
Basis Set
N.def2-TZVP....
N6    0.00000000     0.00000000     1.30942745 Angstrom
N7    0.00000000     0.00000000    -2.77207478 Angstrom
End of Basis
Basis Set
O.def2-TZVP....
O8    0.00000000     0.00000000     2.56273150 Angstrom
End of Basis
Basis Set
H.def2-TZVP....
H9    0.00000000     2.18489057    -1.23595076 Angstrom
H11   0.00000000     2.07042424     1.24633873 Angstrom
End of Basis

End of Input

 &SEWARD

 &SCF
ITER
 50
End of input

 &RASSCF
Symmetry
 4
Spin
 1
nActEl
 10 0 0
Inactive
 15 0 8 0
Ras2
 0 6 1 2
Iterations
 100,100
End of Input

&GRID_IT
 FileOrb=$CurrDir/$Project.RasOrb
 Select
  2:1-6
 NAME=b1

&GRID_IT
 FileOrb=$CurrDir/$Project.RasOrb
 Select
  3:9
 NAME=b2

&GRID_IT
 FileOrb=$CurrDir/$Project.RasOrb
 Select
  4:1-2
 NAME=a2

&GRID_IT
 FileOrb=$CurrDir/$Project.SpdOrb.1
 Select
  2:1-6
 NAME=spin_b1

&GRID_IT
 FileOrb=$CurrDir/$Project.SpdOrb.1
 Select
  3:9
 NAME=spin_b2

&GRID_IT
 FileOrb=$CurrDir/$Project.SpdOrb.1
 Select
  4:1-2
 NAME=spin_a2

-------------------------------------
I am wondering if I'm even setting up this input correctly. I can then visualize images in the spin_b1.lus, spin_b2.lus, and spin_a2.lus files, but I do not know how to translate those images into overall spin densities on the various atoms.
There are other issues, such as my Luscus window (via RealVNC) getting clipped on the right side and bottom, so I cannot access all of the functions, but one thing at a time... I would like to try figuring it out with Luscus before trying Pegamoid.
Thanks--William

---

William Karney
Prof. of Chemistry and Environmental Science
University of San Francisco

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,123

Re: CASSCF spin densities for Luscus visualization

If it's a singlet, the spin density will be zero everywhere. If it's not, it's probably a bug.

karney

Member

From: University of San Francisco

Registered: 2018-09-07

Posts: 4

Website

Re: CASSCF spin densities for Luscus visualization

That does not make sense to me. Yes, it is a singlet, but an open-shell singlet, and I understand the overall net spin density should be zero. There are two nonbonding MOs, each with an occupation of approximately 1.0, and they are very different; one is a pi orbital, and the other is an in-plane p-orbital on nitrogen. It seems like these two MOs should dominate the spin density. There should be alpha spin density from the electron occupying one of the nonbonding MOs, and beta spin density from the electron occupying the other nonbonding MO. Maybe there is something I am missing. Anyway, thank you for you help. I will keep trying to figure this out. --William

---

William Karney
Prof. of Chemistry and Environmental Science
University of San Francisco

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,123

Re: CASSCF spin densities for Luscus visualization

You have alpha in one orbital and beta in another orbital, but you also have the same amount of beta in the first and alpha in the second. You'll probably see it if you print the Slater determinants (PRSD keyword). With M=0, you can't distinguish alpha and beta, and for a singlet there's only M=0.