[CP2K-user] [CP2K:14885] Spin polarized calculation with xTB

[hut... at 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... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

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

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
On Fri, Mar 5, 2021 at 3:42 PM <hut... at chem.uzh.ch> wrote:
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... at chem.uzh.ch
 Winterthurerstrasse 190
 CH-8057 Zürich, Switzerland
 ---------------------------------------------------------------
 
 -----cp... at googlegroups.com wrote: -----
 To: "cp2k" <cp... at googlegroups.com>
 From: "Mauro Sgroi" 
 Sent by: cp... at googlegroups.com
 Date: 03/05/2021 09:33AM
 Subject: [CP2K:14881] Spin polarized calculation with xTB
 
 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
 
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