Molcas Forum

David

Member

Registered: 2017-05-16

Posts: 86

[SOLVED] CASPT2 orbital occupation

Dear Ignacio, when I finished a single point job, it printed CASPT2 and MS-CASPT2 energies at the end of output file, as well as orbital occupation like below, so these occupation corresponding to CASPT2 or MS-CASPT2 energies? or both? If CASPT2 eneries diff MS-CASPT2 a lot, like root flipping problem, how should I choose?

++ Mixed CI coefficients:
  The CI coefficients for the MIXED state nr.   1
--------------------------------------------------------------------------------
 CI COEFFICIENTS LARGER THAN  0.50D-01
  Occupation of active orbitals, and spin coupling
  of open shells. (u,d: Spin up or down).
  SGUGA info is (Midvert:IsyUp:UpperWalk/LowerWalk)
   Conf   SGUGA info Occupation        Coef       Weight
      1 ( 1:1:  1/  1) 2222220000         0.909243         0.826723
      3 ( 1:1:  3/  1) 2222202000        -0.067691         0.004582
      4 ( 1:1:  4/  1) 22222u0d00        -0.068741         0.004725
      6 ( 1:1:  6/  1) 2222200200        -0.080658         0.006506
     16 ( 2:1:  1/  1) 2222u2d000         0.124480         0.015495
     19 ( 2:1:  4/  1) 2222udud00         0.069947         0.004893
     22 ( 2:1:  7/  1) 2222ud0200        -0.066932         0.004480
     37 ( 2:1: 22/  1) 2222udu00d        -0.074599         0.005565
     97 ( 2:1:  2/  3) 22u22d2000         0.050422         0.002542
    100 ( 2:1:  5/  3) 22u22udd00        -0.060902         0.003709
    188 ( 2:1: 13/  5) u2222d0ud0         0.069950         0.004893
    200 ( 2:1: 25/  5) u2222d0u0d         0.069382         0.004814
    216 ( 3:1:  1/  1) 2222022000        -0.069094         0.004774
    256 ( 3:1: 41/  1) 2222020002        -0.060834         0.003701
    336 ( 3:1: 21/  3) 22u2d2u00d         0.077439         0.005997
    666 ( 3:1:  1/ 10) 2202222000        -0.052916         0.002800
    944 ( 3:1: 29/ 15) 02222200ud        -0.052169         0.002722

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,201

Re: [SOLVED] CASPT2 orbital occupation

The "mixed" CI coefficients correspond to the MS-CASPT2 results (the CASPT2 results are based on the CASSCF coefficients). If there is heavy mixing in MS-CASPT2, you just can't assign a particular MS-CASPT2 state to a CASSCF (or CASPT2) one, because they're mixed (just like you can't assign a CASSCF to a particular electronic configuration in some cases). For other ways of "choosing" you could compute state or transition properties with RASSI.

David

Member

Registered: 2017-05-16

Posts: 86

Re: [SOLVED] CASPT2 orbital occupation

Thanks a lot!