# [molpro-user] some question about the CASSCF/MRCI of the excitated state of O2

Xinzheng Yang yangxinzheng at gmail.com
Mon Jun 13 01:44:24 BST 2005

```Dear Ling,

If you want calculate the second excited state, you should specify this state
in the CASSCF and MRCI calculation at the same time with same active space.
The HF calculation should just be used for the ground state.

By the way, I suggest you calculate the ground, first and second excited at the
same time using the state-averaged method to get more reliable
results. you should
calculate two states for each symmetry (2X8=16 states together) using state-
averaged CASSCF method near the equilibrium bond length. Then you can compare
the energies of these states and find the second excited state.

Best wishs,

Xinzheng

On 6/12/05, Ling Tong <yuna at mail.ustc.edu.cn> wrote:
> Dear all users,
>
> I have a urgent question about the CASSCF/MRCI calculation of excitated state of
> O2. Please teach me how to solve it. I am very grateful for your kind help!!
>
> With calculation of different symmetry, state and spin, I find that the first
> excitated state is 1.1 and 1.4, the second excitated state is 2.1 and the third is
> 1.8, is that right?
>
> Now I want to calculation the second excitated state only. How can I write the
> input file?
>
> I have tried the following, I wonder whether it is right.
> hf
> wf,16,1,0
> set,state=2
> casscf
> mrci
>
> In the output file, Reference coefficients greater than 0.0500000
>  ---------------------------------------------
>  22222020          -0.6602408   0.6523411
>  22222002           0.6602408   0.6523411
>  22202022           0.1376040  -0.1645180
>  22022022          -0.1376040  -0.1645180
>  2+2+2-2-          -0.0633604   0.0576398
>  2++22--2           0.0633604   0.0576397
>  22220022           0.0000000  -0.0631207
>  2+2-2+2-          -0.0628380   0.0611710
>  2+-22+-2           0.0628380   0.0611710
>  20222202          -0.0555483  -0.0548570
>  20222220           0.0555483  -0.0548569
>
> Then what is the electron arrange of the second excitated state of O2 ?
>
> Thank you very much.
>
> Sincerely,
> yuna
>
>
>

--
Xinzheng Yang
1071 Clayton Ln, Apt. 1406
Austin, TX 78723

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