From owner-chemistry@ccl.net Sat Aug 20 05:04:01 2016 From: "Marcel Swart marcel.swart/./icrea.cat" To: CCL Subject: CCL:G: Constrained optimization and frequency calculation Message-Id: <-52351-160820050343-5769-IvAJbr+Q0jbpCp5LDjYSvA()server.ccl.net> X-Original-From: Marcel Swart Content-Type: multipart/alternative; boundary="Apple-Mail=_8EC24DBC-9FF4-4BE4-9FDD-E20DC114C24F" Date: Sat, 20 Aug 2016 11:03:35 +0200 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Sent to CCL by: Marcel Swart [marcel.swart^^icrea.cat] --Apple-Mail=_8EC24DBC-9FF4-4BE4-9FDD-E20DC114C24F Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=utf-8 Dear Ankur, I would suggest to have a look at PQS (Baker, Pulay and co-workers) or = QUILD (Swart and co-workers). Both use Baker=E2=80=99s elegant solution to constrained optimizations. Baker, "Constrained optimization in delocalized internal coordinates=E2=80= =9D Journal of Computational Chemistry 18, 1079 (1997) = http://dx.doi.org/10.1002/(SICI)1096-987X(199706)18:8%3C1079::AID-JCC12%3E= 3.0.CO;2-8 PQS: http://www.pqs-chem.com/capabilities.php QUILD: http://www.marcelswart.eu/quild https://www.scm.com/documentation/Quild/index/index Marcel > On 19 Aug 2016, at 22:33, Ankur Kumar Gupta ankkgupt*indiana.edu = wrote: >=20 >=20 > Sent to CCL by: "Ankur Kumar Gupta" [ankkgupt||indiana.edu] > Hello, >=20 > I have been reading about constrained optimization. I have read = several papers related to the topic including the classic Reaction path = Hamiltonian for polyatomic molecules by Miller et al. This and other = research articles describe what is known as 'projection operator' method = to do optimization keeping one or more internal coordinates constant. = Theoretically, we should get 3N-6 non-zero eigenvalues from the force = constant matrix (for a molecule having N nuclei) but if we apply m = number of constraints in the molecule, we should obtain 3N-6-m non-zero = eigenvalues (frequencies). Also, in cases where the constraint = corresponds to a non-equilibrium geometry, there will be coupling = between rotational and vibrational motion due to which the number of = non-zero eigenvalues might change. But for the sake of simplicity, we = can talk about equilibrium geometries only. I use Gaussian 09 and I = observed that the number of non-zero eigenvalues did not change after = constrained optimization. ! > I know there are many computational chemistry softwares out there and = I would like to know if there is a software which can do constrained = optimization correctly and give me the right number and magnitude of = eigenvalues (frequencies) after the optimization. >=20 > Thank you > Ankur >=20 >=20 >=20 > -=3D This is automatically added to each message by the mailing script = =3D- > To recover the email address of the author of the message, please = change>=20>=20>=20 > Subscribe/Unsubscribe:=20>=20>=20 > Job: http://www.ccl.net/jobs=20 > Conferences: = http://server.ccl.net/chemistry/announcements/conferences/ >=20>=20>=20>=20 >=20 _____________________________________ Prof. Dr. Marcel Swart, FRSC ICREA Research Professor at Institut de Qu=C3=ADmica Computacional i Cat=C3=A0lisi (IQCC) Univ. Girona (Spain) COST Action CM1305 (ECOSTBio) chair Girona Seminar 2016 organizer IQCC director RSC Advances associate editor Young Academy of Europe member web http://www.marcelswart.eu vCard addressbook://www.marcelswart.eu/MSwart.vcf --Apple-Mail=_8EC24DBC-9FF4-4BE4-9FDD-E20DC114C24F Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=utf-8 Dear Ankur,

I would suggest to have a look at PQS (Baker, Pulay and = co-workers) or QUILD (Swart and co-workers).
Both = use Baker=E2=80=99s elegant solution to constrained = optimizations.

Baker, "Constrained optimization in delocalized internal = coordinates=E2=80=9D
Journal of Computational = Chemistry 18, 1079 (1997)
http://dx.doi.org/10.1002/(SICI)1096-987X(199706)18:8%3C1079::A= ID-JCC12%3E3.0.CO;2-8

PQS:
http://www.pqs-chem.com/capabilities.php

QUILD:
http://www.marcelswart.eu/quild
https://www.scm.com/documentation/Quild/index/index

Marcel

On 19 Aug 2016, at 22:33, Ankur Kumar Gupta ankkgupt*indiana.edu <owner-chemistry=ccl.net> wrote:


Sent to CCL by: "Ankur Kumar Gupta" [ankkgupt||indiana.edu]
Hello,

I have been reading about = constrained optimization. I have read several papers related to the = topic including the classic Reaction path Hamiltonian for polyatomic = molecules by Miller et al. This and other research articles describe = what is known as 'projection operator' method to do optimization keeping = one or more internal coordinates constant. Theoretically, we should get = 3N-6 non-zero eigenvalues from the force constant matrix (for a molecule = having N nuclei) but if we apply m number of constraints in the = molecule, we should obtain 3N-6-m non-zero eigenvalues (frequencies). = Also, in cases where the constraint corresponds to a non-equilibrium = geometry, there will be coupling between rotational and vibrational = motion due to which the number of non-zero eigenvalues might change. But = for the sake of simplicity, we can talk about equilibrium geometries = only. I use Gaussian 09 and I observed that the number of non-zero = eigenvalues did not change after constrained optimization. !
I know there are many computational chemistry softwares out = there and I would like to know if there is a software which can do = constrained optimization correctly and give me the right number and = magnitude of eigenvalues (frequencies) after the optimization.

Thank you
Ankur



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_____________________________________
Prof. Dr. Marcel Swart, FRSC

ICREA= Research Professor at
Institut de Qu=C3=ADmica = Computacional i Cat=C3=A0lisi (IQCC)
Univ. Girona = (Spain)

COST Action CM1305 (ECOSTBio) = chair
Girona Seminar 2016 organizer
IQCC director
RSC Advances associate editor
Young Academy of Europe member

web
http://www.marcelswart.eu
vCard
addressbook://www.marcelswart.eu/MSwart.vcf






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