xTB + TDDFPT

[Mohamed Madjet]

Hi,

I am trying to run a test calculation for xTB + TDDFPT using the input file

https://github.com/cp2k/cp2k/blob/188010d3feada5e8dc47c3a92ea39282ad338499/tests/QS/regtest-tddfpt-stda/CH2O_tddfpt_stda-xtb-s.inp

The problem is that the TDDFPT excitation energy is negative !!

I am using cp2k 9

Any suggestions how to solve this issue

I am attaching the input and output files.

Thanks

Mohamed

[Jürg Hutter]

Hi

xTB + sTDA needs special care. Have a look also in the original papers by the Grimme group.
I would suggest to use the parameters for exchange and the shift of the virtual spectrum
from those papers as a starting point. Maybe you have to slightly adjust for your type of
molecules.

regards
JH

________________________________________
From: cp...@googlegroups.com <cp...@googlegroups.com> on behalf of Mohamed Madjet <m.ma...@gmail.com>
Sent: Friday, January 20, 2023 2:23 PM
To: cp2k
Subject: [CP2K:18359] xTB + TDDFPT

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[Mohamed Madjet]

Dear Jürg Hutter,

Thanks a lot for your reply and suggestions.

Best,

Mohamed

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