Molcas Forum

Gemma G

Member

Registered: 2016-12-01

Posts: 1

Orthogonality problem using multiple .JobMix inputs for rassi

Hi all,

I want to do a caspt2 and then rassi calculation combining two sets of roots optimised in different casscf runs, these correspond to the 4^T_1 and 4^T_2 states of a Co(II) ion. Currently I am doing caspt2 calculations on each set of roots individually and then a rassi calculation from the two resulting .JobMix files with the following input file:

&RASSI
EJOB
NROF jobiphs
 2 3 3
 1 2 3
 4 5 6
SpinOrbit
EPRG
1.0
MEES

The .JobMix files are read in correctly, and the energies from the caspt2 calculations are seen on the diagonals of the Hamiltonian for the original states. I am then running into a problem because the roots are being assumed to be orthogonal despite having a non-zero overlap. This leads to drastically changed Spin-Free energies and nonsensical states (see below). Are there any keywords or ways to get around this?

Thank you,
Gemma

 HAMILTONIAN MATRIX FOR THE ORIGINAL STATES:
    (Assumed diagonal using JOBIPH energies)

  -2837.86704527
      0.00000000  -2837.86481020
      0.00000000      0.00000000  -2837.86139599
      0.00000000      0.00000000      0.00000000  -2837.83575186
      0.00000000      0.00000000      0.00000000      0.00000000  -2837.82957255
      0.00000000      0.00000000      0.00000000      0.00000000      0.00000000
  -2837.82546832

      OVERLAP MATRIX FOR THE ORIGINAL STATES:

      1.00000000
      0.00000000      1.00000000
      0.00000000      0.00000000      1.00000000
     -0.00060728     -0.00305127      0.00095613      1.00000000
      0.00625043      0.00013073     -0.00035782      0.00000000      1.00000000
      0.00287249      0.00242324      0.00410730      0.00000000     -0.00000000
      1.00000000

  Total energies (spin-free):
::    RASSI State  1     Total energy:  -2858.75240105
::    RASSI State  2     Total energy:  -2849.93624070
::    RASSI State  3     Total energy:  -2846.54204049
::    RASSI State  4     Total energy:  -2829.20980661
::    RASSI State  5     Total energy:  -2825.85646599
::    RASSI State  6     Total energy:  -2817.24570093

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: Orthogonality problem using multiple .JobMix inputs for rassi

Maybe you want to use the HEff keyword instead?

HEFF
    A spin-free effective Hamiltonian is read from JOBIPH instead of being computed. It must have been computed by an earlier program. Presently, this is done by a multi-state calculation using CASPT2. In the future, other programs may add dynamic correlation estimates in a similar way.

In contrast, EJob says explicitly that the Hamiltonian "is assumed to be diagonal".

daishudaishu

Member

Registered: 2019-02-24

Posts: 22

Re: Orthogonality problem using multiple .JobMix inputs for rassi

Is this problem fixed? I met the same problem with my calculation.
https://molcasforum.univie.ac.at/viewtopic.php?id=451