From owner-chemistry@ccl.net Thu Dec 26 10:38:00 2019 From: "Thomas Manz thomasamanz=gmail.com" To: CCL Subject: CCL: crystal orbital Hamilton populations Message-Id: <-53917-191225181915-30492-Y43T7QKpP4tzckOQKIuedQ(0)server.ccl.net> X-Original-From: Thomas Manz Content-Type: multipart/alternative; boundary="000000000000e1c819059a8f7c03" Date: Wed, 25 Dec 2019 16:19:00 -0700 MIME-Version: 1.0 Sent to CCL by: Thomas Manz [thomasamanz*_*gmail.com] --000000000000e1c819059a8f7c03 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi David, > I was told by a PDF that he did not look at any literature pre-1995! Sadly, this meant that he missed crucial papers on point that were not yet digitized! A strange attitude that results in each generation of young scientists re-inventing the wheel which is occasionally round! I think you should probably not try to extrapolate that result to other people. Just because you have had that experience with one post-doctoral fellow, please don't assume that other people are that way also. Sincerely, Tom On Wed, Dec 25, 2019 at 3:43 PM David Mannock dmannock(a)yahoo.com < owner-chemistry * ccl.net> wrote: > Tom, > > A very interesting & truly refreshing message in my inbox on Christmas > day! It was well written with excellent explanations for those of us who > are generalists in CC. I read through it with genuine interest & came awa= y > with some understanding of your purpose. Please keep the list updated of > your findings. > > I will mention one point that I have experienced in studying steroids > which is that there was considerable work in the literature pre-1980 sans > PC. I was told by a PDF that he did not look at any literature pre-1995! > Sadly, this meant that he missed crucial papers on point that were not ye= t > digitized! A strange attitude that results in each generation of young > scientists re-inventing the wheel which is occasionally round! Thanks for > the message & Seasons Greetings to you and your family. > > David Mannock > > On Wednesday, December 25, 2019, 10:33:54 a.m. MST, Thomas Manz > thomasamanz()gmail.com wrote: > > > Dear colleagues, > > Recently, Taoyi Chen and I published a journal article studying the bond > orders of 288 diatomic molecules and ions: T. Chen and T. A. Manz, "Bond > orders of the diatomic molecules," RSC Advances, 9 (2019) 17072-17092 > http://doi.org/10.1039/C9RA00974D (open access). > > While doing the literature review for that article, I was surprised to > find there had been no prior studies of quantum-mechanically computed bon= d > orders across a large set of diatomic molecules. Several prior studies di= d > look at quantum-mechanically computed bond orders for a small set of > diatomics, although the largest set appears to be my own prior study that > included quantum-mechanically computed bond orders for 26 diatomics as pa= rt > of a large study introducing a comprehensive method to compute bond > orders: T. A. Manz, =E2=80=9CIntroducing DDEC6 atomic population analysis= : part 3. > Comprehensive method to compute bond orders,=E2=80=9D RSC Advances, 7 (20= 17) > 45552-45581 http://doi.org/10.1039/c7ra07400j (open access). > > Now, I'm trying to better understand the bonding, non-bonding, and > anti-bonding contributions of individual occupied Kohn-Sham orbitals in > period 2 homodiatomics and other molecules. Due to the s-p mixing in some > of the period 2 homodiatomics, this problem is not as straightforward as > often assumed. For example, the bond order of Be2 is around 0.65 which > occurs because s-p mixing makes the 1 sigma u valence orbital only slight= ly > anti-bonding. (Here, the core orbitals are not included in the numbering > scheme, so 1 sigma g is the lowest energy molecular valence orbital.) > > My question is to what extent approaches like Crystal Orbital Hamilton > Populations (COHP or projected-COHP) or Crystal Orbital Overlap Populatio= ns > (COOP) have been used to study diatomic molecules? Specifically, not just > the integrated total COHP/pCOHP or COOP value, but the value of these > descriptors plotted versus the orbital/band energy? These could be > calculations on an isolated molecule using a localized basis set or > periodic calculations using a single molecule placed in the center of a > large periodic unit cell. In particular, has any prior literature > investigated the claimed correlation between the sign of COHP/pCOHP and t= he > bonding vs. anti-bonding orbital characteristics for molecules whose > bonding, non-bonding, or anti-bonding contributions of individual > orbitals/bands are independently assessed? For example, have any publishe= d > studies demonstrated that the COHP/pCOHP or COOP approaches can accuratel= y > reproduce the bonding, non-bonding, and anti-bonding characteristics of > individual orbitals/bands in period 2 homodiatomics (Li2, Be2, B2, C2, N2= , > O2, F2, and Ne2) or other small molecules? An even more pointed question: > Does the COHP approach predict the 1 sigma u valence orbital in N2 is > bonding, anti-bonding, or approximately non-bonding? How about the 2 sigm= a > g valence orbital in N2? > > Can anyone point me to COHP/pCOHP or COOP studies for isolated molecules > that have tried to assess the reliability of the sign change of these > descriptors for identifying orbitals/bands as bonding, anti-bonding, or > non-bonding? > > Sincerest thanks, > > Tom Manz > --000000000000e1c819059a8f7c03 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
Hi David,

>=C2=A0I was told by a PDF that he did not look at any literature pre-1995= ! Sadly, this meant that he missed crucial papers on point that were not ye= t digitized! A strange attitude that results in each generation of young sc= ientists re-inventing the wheel which is occasionally round!On Wed, Dec 25, 2019 at 3:43 PM David M= annock dmannock(a)yahoo.com <owner-chemistry * ccl.net> wrote:
=
=
Tom,

A very interesting & truly refreshing message in my inbox on Christ= mas day! It was well written with excellent explanations for those of us wh= o are generalists in CC. I read through it with genuine interest & came= away with some understanding of your purpose. Please keep the list updated= of your findings.

I will = mention one point that I have experienced in studying steroids which is tha= t there was considerable work in the literature pre-1980 sans PC. I was tol= d by a PDF that he did not look at any literature pre-1995! Sadly, this mea= nt that he missed crucial papers on point that were not yet digitized! A st= range attitude that results in each generation of young scientists re-inven= ting the wheel which is occasionally round! Thanks for the message & Se= asons Greetings to you and your family.

David Mannock

=20
=20
On Wednesday, December 25, 2019, 10:33:54 a.m. MST, Tho= mas Manz thomasamanz()gmail.= com <owner-chemistry*|*= ccl.net> wrote:


<= div dir=3D"ltr">Dear colleagues,

Recently, Taoyi Chen and I publishe= d a journal article studying the bond orders of 288 diatomic molecules and = ions: T. Chen and T. A. Manz, "Bond orders of the diatomic molecules,&= quot; RSC Advances, 9 (2019) 17072-17092 http://doi.org/10.1039/C9RA0= 0974D (open access).

While doing the literature review for that = article, I was surprised to find there had been no prior studies of quantum= -mechanically computed bond orders across a large set of diatomic molecules= . Several prior studies did look at quantum-mechanically computed bond orde= rs for a small set of diatomics, although the largest set appears to be my = own prior study that included quantum-mechanically computed bond orders for= 26 diatomics as part of a large study introducing a comprehensive method t= o compute bond orders:=C2=A0T. A. Manz, =E2=80=9CIntroducing DDEC6 atomic p= opulation analysis: part 3. Comprehensive method to compute bond orders,=E2= =80=9D RSC Advances, 7 (2017) 45552-45581 http://doi.org/10.1039/c7ra= 07400j (open access).

Now, I'm trying to better under= stand the bonding, non-bonding, and anti-bonding contributions of individua= l occupied Kohn-Sham orbitals in period 2 homodiatomics and other molecules= . Due to the s-p mixing in some of the period 2 homodiatomics, this problem= is not as straightforward as often assumed. For example, the bond order of= Be2 is around 0.65 which occurs because s-p mixing makes the 1 sigma u val= ence orbital only slightly anti-bonding. (Here, the core orbitals are not i= ncluded in the numbering scheme, so 1 sigma g is the lowest energy molecula= r valence orbital.)

My question is to what extent = approaches like Crystal Orbital Hamilton Populations (COHP or projected-COH= P) or Crystal Orbital Overlap Populations (COOP) have been used to study di= atomic molecules? Specifically, not just the integrated total COHP/pCOHP or= COOP value, but the value of these descriptors plotted versus the orbital/= band energy? These could be calculations on an isolated molecule using a lo= calized basis set or periodic calculations using a single molecule placed i= n the center of a large periodic unit cell. In particular, has any prior li= terature investigated the claimed correlation between the sign of COHP/pCOH= P and the bonding vs. anti-bonding orbital characteristics for molecules wh= ose bonding, non-bonding, or anti-bonding contributions of individual orbit= als/bands are independently assessed? For example, have any published studi= es demonstrated that the COHP/pCOHP or COOP approaches can accurately repro= duce the bonding, non-bonding, and anti-bonding characteristics of individu= al orbitals/bands in period 2 homodiatomics (Li2, Be2, B2, C2, N2, O2, F2, = and Ne2) or other small molecules? An even more pointed question: Does the = COHP approach predict the 1 sigma u valence orbital in N2 is bonding, anti-= bonding, or approximately non-bonding? How about the 2 sigma g valence orbi= tal in N2?

Can anyone point me to COHP/pCOHP or CO= OP studies for isolated molecules that have tried to assess the reliability= of the sign change of these descriptors for identifying orbitals/bands as = bonding, anti-bonding, or non-bonding?

Sincerest thanks,

Tom = Manz
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