From owner-chemistry@ccl.net Tue Apr 9 12:02:00 2019 From: "Christoph Riplinger riplinger%faccts.de" To: CCL Subject: CCL:G: G09-Excessive mixing of frozen core and valence orbitals Message-Id: <-53674-190409064011-12816-P2GK8/LVa9GcEdWp4ISlew_+_server.ccl.net> X-Original-From: Christoph Riplinger Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2uBD08dCDeKuHElPJx4xVMiO8OdxcmuVh" Date: Tue, 9 Apr 2019 12:40:02 +0200 MIME-Version: 1.0 Sent to CCL by: Christoph Riplinger [riplinger|-|faccts.de] This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --2uBD08dCDeKuHElPJx4xVMiO8OdxcmuVh Content-Type: multipart/mixed; boundary="0YEWoGY6NhaRAdWXD9TflSeGadeCG0ciY"; protected-headers="v1" > From: Christoph Riplinger To: CCL Subscribers Message-ID: <40967264-bf60-2bf3-1988-59130ea4616a~!~faccts.de> Subject: Re: CCL:G: G09-Excessive mixing of frozen core and valence orbitals References: <53673-190408041808-26172-ElUPykEMPxfmYM7Ji2Eucg~!~server.ccl.net> In-Reply-To: <53673-190408041808-26172-ElUPykEMPxfmYM7Ji2Eucg~!~server.ccl.net> --0YEWoGY6NhaRAdWXD9TflSeGadeCG0ciY Content-Type: multipart/alternative; boundary="------------528BDD18BD8EDB10BCDD65B3" Content-Language: en-US This is a multi-part message in MIME format. --------------528BDD18BD8EDB10BCDD65B3 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Thanks to Susi for the detailed reply and explanation! I would like to additionally mention our recent study https://pubs.rsc.org/en/content/articlehtml/2017/cp/c7cp00836h where we investigate the importance of sub-valence correlation for ligand exchange and association/dissociation reaction enthalpies for light to heavy alkali and alkaline earth metals. For some of these systems artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens was leading to large deviations between canonical / DLPNO-CCSD(T) results and experimental results. As a result of this study we now have more conservative frozen core definitions in ORCA (which removes the above-mentioned large deviations). Also, if "physical core" orbitals are found in the valence region, while "physical valence" orbitals are found in the core region, the corresponding MO pairs are swapped automatically for the subsequent Post-SCF treatment. Best regards, Christoph On 08.04.19 10:17, Susi Lehtola susi.lehtola * alumni.helsinki.fi wrote: > > Sent to CCL by: Susi Lehtola [susi.lehtola%a%alumni.helsinki.fi] > On 4/6/19 1:19 PM, Jacob Berenbeim jacob.berenbeim*|*york.ac.uk wrote: >> >> Sent to CCL by: "Jacob=C2=A0 Berenbeim" [jacob.berenbeim###york.ac.uk]= >> I'm getting inconsistent results with TD-DFT calculations performed >> on organic alkali M+(Na+, K+, Rb+) clusters. These systems have >> previously been optimized and confirmed to be minima at the >> wb97xd/defsvp level using Gaussian 09. A small number of my low >> energy cluster structures are terminating early when running TD-DFT >> from these optimized chk files at the same computational level. I've >> included the termination dialog below. I'm not using a pseudo >> potential for most of the terminating cases. I'd appreciate any >> advice or tips. > > Dear Jacob, > > > this is a well-known issue in calculations with alkali metals: the > definition of core orbitals by the orbital eigenvalue can lead to the > wrong orbitals being included in the active space. This problem has bee= n > described e.g. by Petrie in J. Phys. Chem. A 102, 6138 (1998) and by > Rassolov, Pople, Redfern and Curtiss in Chemical Physics Letters 350, > 573 (2001). > > The problem is that the semi-core orbitals of the alkali metals can hav= e > orbital energies that are higher than the valence orbitals of other > species, which means that the valence orbitals end up frozen while the > semi-core orbitals are included in the active space of the TD-DFT > calculation. > > This can be solved either by redefining the core orbitals by studying > the orbital character visually or via Mulliken analysis like Rassolov e= t > al, or by increasing the size of the active space such that all valence= > orbitals are included therein. > > Pierre Archirel already suggested using td=3Dfull, which means dropping= > the active space altogether. A less costly option would be to use just = a > slightly larger active space e.g. the inner noble gas core. --=20 FAccTs GmbH Rolandstrasse 67, 50677 K=C3=B6ln Amtsgericht K=C3=B6ln HRB 88406 Gesch=C3=A4ftsf=C3=BChrer: Dr. Christoph Riplinger https://www.faccts.de --------------528BDD18BD8EDB10BCDD65B3 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable

Thanks to Susi for the detailed reply and explanation!

I would like to additionally mention our recent study

https://pubs.rsc.org/en/content/= articlehtml/2017/cp/c7cp00836h

where we investigate the importance of sub-valence correlation for ligand exchange and association/dissociation reaction enthalpies for = light to heavy alkali and alkaline earth metals. For some of these systems artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens was leading to large deviations between canonical / DLPNO-CCSD(T) results and experimental results.

As a result of this study we now have more conservative frozen core definitions in ORCA (which removes the above-mentioned large deviations). Also, if "physical core" orbitals are found in the valence region, while "physical valence" orbitals are found in the core region, the corresponding MO pairs are swapped automatically for the subsequent Post-SCF treatment.

Best regards,

Christoph

On 08.04.19 10:17, Susi Lehtola susi.lehtola * alumni.helsinki.fi wrote:

Sent to CCL by: Susi Lehtola [susi.lehtola%a%alumni.helsinki.fi]
On 4/6/19 1:19 PM, Jacob Berenbeim jacob.berenbeim*|*york.ac.uk wrote:

Sent to CCL by: "Jacob=C2=A0 Berenbeim" [jacob.berenbeim###york.ac.uk]
I'm getting inconsistent results with TD-DFT calculations performed
on organic alkali M+(Na+, K+, Rb+) clusters. These systems have previously been optimized and confirmed to be minima at the wb97xd/defsvp level using Gaussian 09. A small number of my low energy cluster structures are terminating early when running TD-DFT from these optimized chk files at the same computational level. I've included the termination dialog below. I'm not using a pseudo potential for most of the terminating cases. I'd appreciate any advice or tips.

Dear Jacob,


this is a well-known issue in calculations with alkali metals: the
definition of core orbitals by the orbital eigenvalue can lead to the
wrong orbitals being included in the active space. This problem has been
described e.g. by Petrie in J. Phys. Chem. A 102, 6138 (1998) and by
Rassolov, Pople, Redfern and Curtiss in Chemical Physics Letters 350,
573 (2001).

The problem is that the semi-core orbitals of the alkali metals can have
orbital energies that are higher than the valence orbitals of other
species, which means that the valence orbitals end up frozen while the
semi-core orbitals are included in the active space of the TD-DFT
calculation.

This can be solved either by redefining the core orbitals by studying
the orbital character visually or via Mulliken analysis like Rassolov et
al, or by increasing the size of the active space such that all valence
orbitals are included therein.

Pierre Archirel already suggested using td=3Dfull, which means dropping
the active space altogether. A less costly option would be to use just a
slightly larger active space e.g. the inner noble gas core. 
--=20
FAccTs GmbH
Rolandstrasse 67, 50677 K=C3=B6ln
Amtsgericht K=C3=B6ln HRB 88406
Gesch=C3=A4ftsf=C3=BChrer: Dr. Christoph Riplinger
https:/=
/www.faccts.de
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