Spin polarized calculation with xTB

[Mauro Sgroi]

Dear all,

I'm trying to understand if it is possible to use xTB to perform spin polarized calculations.

If yes, which is the right way to proceed?

Is there an howto to follow?

Thannks a lot and best regards,

Mauro Sgroi

Centro Ricerche FIAT

Italy

[hut...@chem.uzh.ch]

Hi

you can use unrestricted calculations also with xTB. However,
the xTB Hamiltonian doesn't have a spin dependence. So what you
get is the same as using a restricted open shell calculation.
Unrestricted is double the work, but can use OT methods.
Restricted open shell (ROKS will not work btw) will need
diagonalization and smearing. What is more efficient in the end
might depend on your system.

best regards

Juerg Hutter
--------------------------------------------------------------
Juerg Hutter Phone : ++41 44 635 4491
Institut für Chemie C FAX : ++41 44 635 6838
Universität Zürich E-mail: hut...@chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

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From: "Mauro Sgroi"
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Date: 03/05/2021 09:33AM
Subject: [CP2K:14881] Spin polarized calculation with xTB

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[Mauro Sgroi]

Dear Prof. Hutter,

thanks a lot for the clarification.

Best regards,

Mauro Sgroi.

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[Pierre-André Cazade]

Dear Juerg,

It's a very interesting topic. Provided what you described in your reply, is it possible to use xTB for a triplet state? If yes, is it necessary to use UKS, since the Hamiltonian doesn't have spin-dependence?

Regards,

Pierre

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[hut...@chem.uzh.ch]

Hi

you can calculate a triplet using UKS. For xTB the results should
show equal orbital energies for alpha and beta spin, even though
the occupations will be different.

regards

Juerg

--------------------------------------------------------------
Juerg Hutter Phone : ++41 44 635 4491
Institut für Chemie C FAX : ++41 44 635 6838
Universität Zürich E-mail: hut...@chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

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To: cp...@googlegroups.com
From: "Pierre-André Cazade"
Sent by: cp...@googlegroups.com
Date: 03/05/2021 05:16PM
Subject: Re: [CP2K:14885] Spin polarized calculation with xTB

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