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rikaaardoss

Member

Registered: 2020-07-29

Posts: 20

chemical bond in excited states using Multiwfn and Orca

Hi all, I am interested in analyzing chemical bonding in excited states using Multiwfn. For this I have done casscf calculations in ORCA, the system I am studying is triplet in its ground state (T0), however I am not getting the wave function of the first triplet excited state (T1), is there any way to obtain this function?, here is the input I am using:

! def2-TZVP def2/J
! moread
%moinp "c2o_t.gbw"
%MaxCore 20000
%scf
     TolG 1.0e-04
     TolE 1.0e-06
     maxiter 500
end
%casscf
        nel 14
        norb 10
        mult 3
        nroots 3
        weights[1] = 1.0,0.0,0.0
end

%pal nprocs 10
end
*xyz 0 3
C        0.000000000      0.000000000      0.000000000
C        0.000000000     -1.369900105      0.000000000
O        0.000000000      1.162700089      0.000000000

I figured I should change the weight of the state, so I would have this: " weights[1] = 0.0,1.0,0.0 "

However, when I get the molden file and check the occupancies of the natural orbitals both files are very similar.

Thanks advance for any help provided.

R.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: chemical bond in excited states using Multiwfn and Orca

Usually, to calculate excited state by CASSCF, you should use state-average treatment, otherwise due to variational collapse, despite you set initial weight of T1 as 1.0, the wavefunction may finally converge to T0.

rikaaardoss

Member

Registered: 2020-07-29

Posts: 20

Re: chemical bond in excited states using Multiwfn and Orca

So, from what I understand, there is no way to obtain the wave function of the system in the excited state T1, but I could only study it in T0.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: chemical bond in excited states using Multiwfn and Orca

So, from what I understand, there is no way to obtain the wave function of the system in the excited state T1, but I could only study it in T0.

You should set both first and second states with weight of 0.5. Then both the states should be able to solve.