From owner-chemistry@ccl.net Tue Dec 31 03:28:01 2024 From: "=?utf-8?B?TWFyaXVzeiBSYWRvxYQ=?= mariusz.radon _ uj.edu.pl" To: CCL Subject: CCL: Yamaguchi's approximate spin projection (AP) method Message-Id: <-55285-241231032707-19122-iXdCCVzPCADFWmys5e0WPQ(_)server.ccl.net> X-Original-From: =?utf-8?B?TWFyaXVzeiBSYWRvxYQ=?= Content-Language: en-US Content-Type: multipart/signed; boundary="Apple-Mail=_49AE98AF-8B0B-4EA2-BF5C-A105831C394B"; protocol="application/pgp-signature"; micalg=pgp-sha256 Date: Tue, 31 Dec 2024 08:26:48 +0000 MIME-Version: 1.0 Sent to CCL by: =?utf-8?B?TWFyaXVzeiBSYWRvxYQ=?= [mariusz.radon]_[uj.edu.pl] --Apple-Mail=_49AE98AF-8B0B-4EA2-BF5C-A105831C394B Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Dear Akhilesh: > On 28 Dec 2024, at 09:39, Akhilesh Sharma sharmaakhil9250 ~ gmail.com = wrote: >=20 > Can we utilize single-point electronic energies of the BS and triplet = spin > states by using the singlet state optimized geometry for the AP = method? >=20 > Or is it necessary to calculate the electronic energies for the BS and > triplet spin states at their respective optimized geometries to = correctly > apply the AP method? >=20 > Any guidance on how to proceed in this situation would be greatly > appreciated. >=20 You should use the same geometry for both states. The AP method is a = correction of BS energy for the contribution of the contaminating = (admixed) triplet state. Utilizing the energy of this state computed in = a different geometry (i.e., optimizing it separately) would not make = sense. Thus you can and should use the geometry of the BS =E2=80=9Cstate=E2=80=9D= to compute the energy of the triplet state. In principle, it would be = better to find the minimum of the AP-corrected energy, but I am not = aware of any program which could perform such an optimization in = practice. Best regards, Mariusz Radon -- Mariusz Radon, Ph.D., D.Sc. Associate Professor Faculty of Chemistry, Jagiellonian University Address: Gronostajowa 2, 30-387 Krakow, Poland Room C1-06, Phone: 48-12-686-24-89 E-mail: mradon,chemia.uj.edu.pl (mariusz.radon,uj.edu.pl) Web: https://tungsten.ch.uj.edu.pl/~mradon ORCID: https://orcid.org/0000-0002-1901-8521 --Apple-Mail=_49AE98AF-8B0B-4EA2-BF5C-A105831C394B Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- iHUEAREIAB0WIQR+DG5LsRgBNXmBGWCmgNuaxEDwbQUCZ3OqyAAKCRCmgNuaxEDw bTw/AP9qUUOrc56sAakWryImj8kUhpAh9zr/H85/sDniqcP/dAD8CHAVFIp03jBp sApq6rIybBg8S8HfcP3A74imUFI1lUg= =rA+J -----END PGP SIGNATURE----- --Apple-Mail=_49AE98AF-8B0B-4EA2-BF5C-A105831C394B-- From owner-chemistry@ccl.net Tue Dec 31 13:07:01 2024 From: "Marcel Swart marcel.swart * gmail.com" To: CCL Subject: CCL: Yamaguchi's approximate spin projection (AP) method Message-Id: <-55286-241231053853-11979-j2uArWgKZoTGTAQnkf6opg,server.ccl.net> X-Original-From: Marcel Swart Content-Transfer-Encoding: 7bit Content-Type: multipart/alternative; boundary=Apple-Mail-1C711850-815D-4826-B1A6-6F9B4B91E09A Date: Tue, 31 Dec 2024 11:38:33 +0100 Mime-Version: 1.0 (1.0) Sent to CCL by: Marcel Swart [marcel.swart.:.gmail.com] --Apple-Mail-1C711850-815D-4826-B1A6-6F9B4B91E09A Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable Quild (https://www.marcelswart.eu/quild/index.html) ca= n do the optimization and vibrational frequencies for spin-decontamination (= and single-point energy of course), all automagically.

Quild is included within the AMS package.

More info on spin-decontamination with= it:

=
Marcel Swart
ICREA, Univ. Girona
= Full Professor 
www.marcel= swart.eu
marcel.swart^_^icrea.cat

Disclaimer:
I&nbs= p;completely understand if you don't have time to work on thi= s until normal business hours. I won't be expecting an&n= bsp;immediate response.

On 31 Dec 2024, at 10:40, Mariusz Rado=C5= =84 mariusz.radon _ uj.edu.pl <owner-chemistry^_^ccl.net> wrote:

=
=EF=BB=BFDear Akhilesh:

O= n 28 Dec 2024, at 09:39, Akhilesh Sharma sharmaakhil9250 ~ gmail.com <own= er-chemistry[A]ccl.net> wrote:

Can we u= tilize single-point electronic energies of the BS and triplet spin
states by using the singlet st= ate optimized geometry for the AP method?

Or is it necessary to calculate the electronic energies for the BS and
triplet spin states at th= eir respective optimized geometries to correctly
apply the AP method?

Any guidance on how to proceed in this situation would be greatly
appreciated.
=

<= /span>
You should use the same geometry for both states. The AP met= hod is a correction of BS energy for the contribution of the contaminating (= admixed) triplet state. Utilizing the energy of this state computed in a dif= ferent geometry (i.e., optimizing it separately) would not make sense.

Thus you can and should use the geometry of the B= S =E2=80=9Cstate=E2=80=9D to compute the energy of the triplet state. In pri= nciple, it would be better to find the minimum of the AP-corrected energy, b= ut I am not aware of any program which could perform such an optimization in= practice.

Best regards,
Ma= riusz Radon


--
<= span>Mariusz Radon, Ph.D., D.Sc.
Associate Professor<= br>Faculty of Chemistry, Jagiellonian University

Address: Gronostajowa 2, 30-387 Krakow, Poland
R= oom C1-06, Phone: 48-12-686-24-89
E-mail: mradon[A]chemia.uj= .edu.pl (mariusz.radon[A]uj.edu.pl)
Web: https://tungsten.ch= .uj.edu.pl/~mradon
ORCID: https://orcid.org/0000-0002-1901-8= 521

<signature.asc>
= --Apple-Mail-1C711850-815D-4826-B1A6-6F9B4B91E09A--