What causes the warnings in one kind of ECD calculation but not in another

Find answers or ask questions regarding Dalton calculations.
Please upload an output file showing the problem, if applicable.
(It is not necessary to upload input files, they can be found in the output file.)

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hjaaj
Posts: 394
Joined: 27 Jun 2013, 18:44
First name(s): Hans Jørgen
Middle name(s): Aagaard
Last name(s): Jensen
Affiliation: Universith of Southern Denmark
Country: Denmark

Re: What causes the warnings in one kind of ECD calculation but not in another

Post by hjaaj » 06 Oct 2020, 14:38

This indicates that you have a so-called singlet instability, which is not seen that often. It means that you can get lower HF energy by using complex orbitals (not implemented in Dalton), similar to that a triplet instability means UHF gives lower energy than RHF.
Conclusion: you need to use MCSCF to get reasonable values.

xiongyan21
Posts: 298
Joined: 24 Sep 2014, 08:36
First name(s): yan
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Affiliation: CENTRAL CHINA NORMAL UNIVERSITY
Country: China

Re: What causes the warnings in one kind of ECD calculation but not in another

Post by xiongyan21 » 10 Oct 2020, 06:09

I have used mp2 natural orbitals for this. Does it exacerbate the situation?

Very Best regards!

hjaaj
Posts: 394
Joined: 27 Jun 2013, 18:44
First name(s): Hans Jørgen
Middle name(s): Aagaard
Last name(s): Jensen
Affiliation: Universith of Southern Denmark
Country: Denmark

Re: What causes the warnings in one kind of ECD calculation but not in another

Post by hjaaj » 12 Oct 2020, 09:50

Your attached output files above are all for HF.
I assume you have performed MCSCF calculations since then, and choosing active space based on MP2 occupation number improve the situation in all calculations I have seen. Note: if two MP2 occupation numbers are close, e.g. 1.974 and 1.977, you should include both, but so accurate is MP2 not. With respect to "close": for the strongly occupied orbitals you should judge from "2 - occupation number", i.e. 0.026 and 0.023 in may example above.

xiongyan21
Posts: 298
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Affiliation: CENTRAL CHINA NORMAL UNIVERSITY
Country: China

Re: What causes the warnings in one kind of ECD calculation but not in another

Post by xiongyan21 » 18 Nov 2020, 10:02

Dear Prof. Jensen
I have only found the DFT example but not the MCSCF input in the test.
Where can I find it?

Very Best Regards!

xiongyan21
Posts: 298
Joined: 24 Sep 2014, 08:36
First name(s): yan
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Affiliation: CENTRAL CHINA NORMAL UNIVERSITY
Country: China

Re: What causes the warnings in one kind of ECD calculation but not in another

Post by xiongyan21 » 19 Nov 2020, 04:30

I used the following input to calculate ECD of the above molecule
**DALTON INPUT
.RUN RESPONSE
**INTEGRALS
.DIPLEN
**WAVE FUNCTION INPUT
.DFT
B3LYP
*SCF INPUT
.MAX DIIS
100
**PROPERTIES
.OPTROT
*ABALNR
.DAMPING
0.0045566
.FREQUENCIES
5
0.050000 0.0525 0.055 0.0575 0.06
**END OF DALTON INPUT

but the program finishes without the intended calculation
| End of Wave Function Section (SIRIUS) |
`---------------------------------------'



.------------------------------------------------.
| Starting in Dynamic Property Section (RESPONS) |
`------------------------------------------------'


------------------------------------------------------------------------------
RESPONSE - an MCSCF, MC-srDFT, DFT, and SOPPA response property program
------------------------------------------------------------------------------


-------- OUTPUT FROM RESPONSE INPUT PROCESSING --------




SCF energy : ...
-- inactive part : ...
-- nuclear repulsion : ...


*****************************************
*** DFT response calculation (TD-DFT) ***
*****************************************


Total CPU time used in RESPONSE: 0.00 seconds
Total wall time used in RESPONSE: 0.00 seconds


.-------------------------------------------.
| End of Dynamic Property Section (RESPONS) |
`-------------------------------------------'

Total CPU time used in DALTON: 5 minutes 28 seconds
Total wall time used in DALTON: 5 minutes 28 seconds

hjaaj
Posts: 394
Joined: 27 Jun 2013, 18:44
First name(s): Hans Jørgen
Middle name(s): Aagaard
Last name(s): Jensen
Affiliation: Universith of Southern Denmark
Country: Denmark

Re: What causes the warnings in one kind of ECD calculation but not in another

Post by hjaaj » 22 Nov 2020, 16:13

Your ECP input does not work because you need .RUN PROPERTIES instead of .RUN RESPONSE to get results from the **PROPERTIES module.

xiongyan21
Posts: 298
Joined: 24 Sep 2014, 08:36
First name(s): yan
Last name(s): xiong
Affiliation: CENTRAL CHINA NORMAL UNIVERSITY
Country: China

Re: What causes the warnings in one kind of ECD calculation but not in another

Post by xiongyan21 » 23 Nov 2020, 10:39

Dear Prof. Jensen
Thanks a lot.
It works for the above molecule. I will recalculate this by the change of frequencies suitable for this molecule and compare the Dalton results with the published theoretical and experimental ones, so that I can calculate that for a pesticide.

Very Best Regards!

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