From owner-chemistry@ccl.net Tue Jul 5 12:49:01 2016 From: "Tandon Swetanshu tandons%tcd.ie" To: CCL Subject: CCL: Coupling constant (Jab) - Why more unpaired electrons means a smaller coupling? Message-Id: <-52278-160705114913-1135-ngK0Xed+e+MjlR1kQpa1Zw-#-server.ccl.net> X-Original-From: Tandon Swetanshu Content-Type: multipart/alternative; boundary=001a114168d673e9020536e564e9 Date: Tue, 5 Jul 2016 16:49:03 +0100 MIME-Version: 1.0 Sent to CCL by: Tandon Swetanshu [tandons.__.tcd.ie] --001a114168d673e9020536e564e9 Content-Type: text/plain; charset=UTF-8 Hi Dr. Kraemer, Thanks a lot for your help. Regards, Swetanshu. On 30 June 2016 at 18:03, Tobias Kraemer t.kraemer:+:hw.ac.uk < owner-chemistry__ccl.net> wrote: > > Sent to CCL by: "Tobias Kraemer" [t.kraemer|hw.ac.uk] > Dear Swetanshu, > > > in your case you are dealing with an overdetermined system of linear > equations, i.e. there are more equations than needed to solve for all > coupling constants (J_ab). You can use the so-called singular value > decompostion (SVD) method to solve for the best set of J_ab. Basically you > consider all your equations resulting from all combinations of spin > configurations (high-spin plus numerous broken-symmetry solutions). > MATLAB can do this job for you, you only have to input the matrices > with the coefficients and J_ab variables, run SVD and you'll have your > result. > > I can't find any particular literature on this at the moment, but there are > plenty of papers on this. This one here by Michl et al. mentions SVD: > > Toward (car)boranebased molecular magnetsm Theor. Chem. Acc. (2015) 134:9 > > Hope this helps > > > Tobi > > > > > Dr. Tobias Kraemer MRSC > Research Associate > Institute of Chemical Sciences > School of Engineering & Physical Sciences > Heriot-Watt University > Edinburgh EH14 4AS > United Kingdom > email: t.kraemer . hw.ac.uk > phone: +44 (0)131 451 3259 > > > > >Hi Henrique, > >Thanks again for the advice. I think however, that you were referring to > >coming up with different models (each generally having a different number > >of coupling constants) before proceeding with the calculation of coupling > >constants (please correct me if I am wrong). For the system I am studying, > >I have selected the model. The number of equations I have for calculating > >the coupling constants is much greater than the number of coupling > >constants that I need to calculate. Depending upon the set of equations I > >choose, I get a different set of J values. Can you please guide me as to > >how should I choose the appropriate set of equation for calculating the J > >values. > >Thanks again, > >Swetanshu. > > > > "Henrique C. S. Junior henriquecsj~~gmail.com" wrote: > > > > Sent to CCL by: "Henrique C. S. Junior" [henriquecsj+*+gmail.com] > > --001a113dd29432bd3c053668ae65 > > Content-Type: text/plain; charset=UTF-8 > > Content-Transfer-Encoding: quoted-printable > > > > Hi, Swetanshu, > > You don't need the coupling constants before, but you need to perform a > > study to understand what couplings are relevant to your system (to figure > > out how complex the Hamiltonian will be). After you understood your > system, > > you can use, as an example, the software DAVE[1] to see if your model > fits > > your experimental data. If not, you have to re-think your system and try > > again to obtain a better fit. > > > > [1] - https://www.ncnr.nist.gov/dave/download.html > > > > 2016-06-28 16:53 GMT-03:00 Tandon Swetanshu tandons-,-tcd.ie < > > owner-chemistry.:.ccl.net>: > > > > > Hi Henrique, > > > > > > Thanks a lot for the insight. I have a small doubt. Before obtaining > the > > > susceptibility curve, we need to obtain the coupling constant. So can't > w= > > e > > > just compare the calculated coupling constants with the experimental > ones= > > ? > > > > > > Thanks again, > > > Swetanshu. > > > > > > On 26 June 2016 at 22:05, Henrique C. S. Junior henriquecsj(~) > gmail.com > < > > > owner-chemistry!!ccl.net> wrote: > > > > > >> Hi, Swetanshu, > > >> It is not an easy task to decide what configuration is correct to > > >> describe the magnetic couplings in a polynuclear system. The best > approa= > > ch > > >> is to compare the various solutions with an experimental magnetic > > >> susceptibility curve using a statistical fit software (like origin). > > >> > > >> > > >> > > >> ---------- > > >> *Henrique C. S. Junior* > > >> Qu=C3=ADmico Industrial - UFRRJ > > >> Mestrando em Qu=C3=ADmica Inorg=C3=A2nica - UFRRJ > > >> Centro de Processamento de Dados - PMP > > >> > > >> > > >> ------------------------------ > > >> > From: owner-chemistry=C3=8Cl.net > > >> To: henriquecsjgmail.com > > >> Subject: CCL: Coupling constant (Jab) - Why more unpaired electrons > mean= > > s > > >> a smaller coupling? > > >> Date: Fri, 24 Jun 2016 11:45:36 +0100 > > >> > > >> Hi All, > > >> > > >> I have a question somewhat related to this topic. When working out the > J > > >> values in a system with more than 3 metal atoms, there are many > differen= > > t > > >> solutions. Each solutions is obtained by choosing a different set of > > >> equations. From the above discussion it seems to me that the large > > >> differeence in the solutions are due to the large number of unpaired > > >> electrons and the reduction in the spacing between levels at higher > ener= > > gy. > > >> Due to this, depending upon the states under consideration the J > values > > >> obtained would differ (please correct me if I am wrong). But how does > on= > > e > > >> decide as to which set of solution is appropriate. > > >> > > >> Thanks, > > >> Swetanshu. > > >> > > >> On 12 June 2016 at 00:27, James Buchwald buchwja/rpi.edu < > > >> owner-chemistry,ccl.net> wrote: > > >> > > >> Hi Henrique, > > >> > > >> The diminishing Jab that you're predicting assumes that (E[HS] - > E[BS]) > > >> does not grow as quickly as the spin term in the denominator. > Depending= > > on > > >> the system, this is not necessarily the case, and the energy spacing > can > > >> grow faster. > > >> > > >> The reason that the equations appear to cause this is that the > > >> Heisenberg-Dirac-van Vleck Hamiltonian (which the three equations were > > >> derived from) has a "spin ladder" of solutions ranging from the low- > spin= > > to > > >> the high-spin states. If your low-spin state is a singlet, you'll > also > > >> have triplets, pentets, and so on until you reach the high-spin state. > > >> Similarly, if you start from a doublet, you'll have intermediate > quartet= > > s, > > >> etc. > > >> > > >> As you introduce more and more unpaired electrons, the spin of the > > >> high-spin state increases - but all of the intermediate states between > t= > > he > > >> high-spin and low-spin limits still exist. You can work out the > splitti= > > ng > > >> between these individual states in terms of J, and what ends up > happenin= > > g > > >> is that the states spread out. The denominator essentially corrects > for > > >> that spacing, rather than saying anything about the strength of the > > >> magnetic coupling. > > >> > > >> Best, > > >> James > > >> > > >> On 06/11/2016 05:54 PM, Henrique C. S. Junior henriquecsj-x-gmail.com > > >> wrote: > > >> > > >> I hope this is not a "homework" question, but I'm having a bad time > > >> trying to figure this out. > > >> Available literature proposes 3 equations to calculate the coupling > > >> constant during a Broken-Symmetry approach: > > >> > > >> J(1) =3D -(E[HS]-E[BS])/Smax**2 > > >> J(2) =3D -(E[HS]-E[BS])/(Smax*(Smax+1)) > > >> J(3) =3D -(E[HS]-E[BS])/(HS-BS) > > >> > > >> I'm intrigued by the fact that, from the equations, the more the > system > > >> have unpaired electrons, the minor will be Jab. Why does this happen? > > >> Doesn't more unpaired electrons increase magnetic momenta (and an > increa= > > se > > >> in magnetic coupling)? > > >> > > >> -- > > >> *Henrique C. S. Junior* > > >> Qu=C3=ADmico Industrial - UFRRJ > > >> Mestrando em Qu=C3=ADmica Inorg=C3=A2nica - UFRRJ > > >> Centro de Processamento de Dados - PMP > > >> > > >> > > >> -- > > >> James R. Buchwald > > >> Doctoral Candidate, Theoretical Chemistry > > >> Dinolfo Laboratory > > >> Dept. of Chemistry and Chemical Biology > > >> Rensselaer Polytechnic Institutehttp://www.rpi.edu/~buchwj > > >> > > >> > > >> > > > > > > > > > --=20 > > *Henrique C. S. Junior* > > Qu=C3=ADmico Industrial - UFRRJ > > Mestrando em Qu=C3=ADmica Inorg=C3=A2nica - UFRRJ > > Centro de Processamento de Dados - PMP > > > > --001a113dd29432bd3c053668ae65 > > Content-Type: text/html; charset=UTF-8 > > Content-Transfer-Encoding: quoted-printable > > > >
family:monospac= > > e,monospace">Hi,=C2=A0 family:arial,san= > > s-serif">Swetanshu,
style=3D"font-= > > family:monospace,monospace"> family:ari= > > al,sans-serif">You don't need the coupling constants before, but you > ne= > > ed to perform a study to understand what couplings are relevant to your > sys= > > tem (to figure out how complex the Hamiltonian will be). After you > understo= > > od your system, you can use, as an example, the software DAVE[1] to see > if = > > your model fits your experimental data. If not, you have to re-think your > s= > > ystem and try again to obtain a better fit.
class=3D"gmail= > > _default" style=3D"font-family:monospace,monospace"> siz= > > e:12.8px;font-family:arial,sans-serif">

class=3D"gmail_qu= > > ote">2016-06-28 16:53 GMT-03:00 Tandon Swetanshu tandons-,- href=3D"http:= > > //tcd.ie">tcd.ie < chemistr= > > y.:.ccl.net" target=3D"_blank">owner-chemistry.:.ccl.net>: >
> ockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px > #= > > ccc solid;padding-left:1ex">
Hi Henrique, > > >
Thanks a lot for the insight. I have a small doubt. Before > obtai= > > ning the susceptibility curve, we need to obtain the coupling constant. > So = > > can't we just compare the calculated coupling constants with the > experi= > > mental ones?

Thanks again,
Swetanshu.
>
> class=3D"gmail_extra">
On 26 June 2016 at > 22:= > > 05, Henrique C. S. Junior henriquecsj(~) target= > > =3D"_blank">gmail.com < che= > > mistry!!ccl.net" target=3D"_blank">owner-chemistry!!ccl.net> > = > > wrote:
.8ex;bord= > > er-left:1px #ccc solid;padding-left:1ex"> > > > > > >
face=3D"Couri= > > er New, sans-serif">Hi, > S= > > wetanshu,
> > pan style=3D"font-size:15px;line-height:21.3px">It is not an easy task to > d= > > ecide what configuration is correct to describe the magnetic couplings in > a= > > polynuclear system. The best approach is to compare the various > solutions = > > with an experimental magnetic susceptibility curve using a statistical > fit = > > software (like origin).
size:15px;lin= > > e-height:21.3px">


New">-= > > ---------
> Henri= > > que C. S. Junior
face=3D"Courier= > > New">Qu=C3=ADmico Industrial - UFRRJ
Mestrando em Qu=C3=ADmica > Inorg=C3= > > =A2nica - UFRRJ
face=3D"Courie= > > r New">Centro de Processamento de Dados - PMP


>
= > > > From: owner-chemistry=C3=8Cl.net
To: href=3D"http://henriquecsjg= > > mail.com" target=3D"_blank">henriquecsjgmail.com
Subject: CCL: > Coupl= > > ing constant (Jab) - Why more unpaired electrons means a smaller > coupling?<= > > br>Date: Fri, 24 Jun 2016 11:45:36 +0100

Hi All, > > v>
I have a question somewhat related to this topic. When > wor= > > king out the J values in a system with more than 3 metal atoms, there are > m= > > any different solutions.=C2=A0 Each solutions is obtained by choosing a > dif= > > ferent set of equations. From the above discussion it seems to me that > the = > > large differeence in the solutions are due to the large number of > unpaired = > > electrons and the reduction in the spacing between levels at higher > energy.= > > Due to this, depending upon the states under consideration the J values > ob= > > tained would differ (please correct me if I am wrong). But how does one > dec= > > ide as to which set of solution is appropriate.

> > iv>Thanks,
Swetanshu.

On 12 June 2016 at > 00:27= > > , James Buchwald buchwja/ target=3D"_blank">rpi.e= > > du < tar= > > get=3D"_blank">owner-chemistry,ccl.net> wrote:
> > style=3D"border-left:1px solid rgb(204,204,204);padding-left:1ex"> > > =20 > > =20 > > =20 > >
> > Hi Henrique,
> >
> > The diminishing Jab that you're predicting assumes that (E[HS] - > > E[BS]) does not grow as quickly as the spin term in the > > denominator.=C2=A0 Depending on the system, this is not necessarily > the > > case, and the energy spacing can grow faster.
> >
> > The reason that the equations appear to cause this is that the > > Heisenberg-Dirac-van Vleck Hamiltonian (which the three equations > > were derived from) has a "spin ladder" of solutions ranging > f= > > rom the > > low-spin to the high-spin states.=C2=A0 If your low-spin state is a > > singlet, you'll also have triplets, pentets, and so on until you > > reach the high-spin state.=C2=A0 Similarly, if you start from a > doublet= > > , > > you'll have intermediate quartets, etc.
> >
> > As you introduce more and more unpaired electrons, the spin of the > > high-spin state increases - but all of the intermediate states > > between the high-spin and low-spin limits still exist.=C2=A0 You can > wo= > > rk > > out the splitting between these individual states in terms of J, and > > what ends up happening is that the states spread out.=C2=A0 The > > denominator essentially corrects for that spacing, rather than > > saying anything about the strength of the magnetic coupling.
> >
> > Best,
> > James
> >
> >
On 06/11/2016 05:54 PM, Henrique C. S. > > Junior target=3D"_blank">h= > > enriquecsj-x-gmail.com wrote:
> >
> >
> >
> >
> >
I > > hope this is not a "homework" question, but > I'm= > > having a > > bad time trying to figure this out.
> >
Available > > literature proposes 3 equations to calculate the coupling > > constant during a Broken-Symmetry approach:
> >

> >
> >
J(1) > > =3D -(E[HS]-E[BS])/Smax**2
> >
J(2) > > =3D -(E[HS]-E[BS])/(Smax*(Smax+1))
> >
J(3) > > =3D -(E[HS]-E[BS])/(<S**2>HS-<S**2>BS) > > v> > >

> >
> >
I'm > > intrigued by the fact that, from the equations, the more > > the system have unpaired electrons, the minor will be Jab. > > Why does this happen? Doesn't more unpaired electrons > > increase magnetic momenta (and an increase in magnetic > > coupling)?
color=3D"= > > #888888"> > >
colo= > > r=3D"#888888"> > >

> >
> > --
> >
> >
> >
> >
> >
> >
style=3D"color:rgb(139,139,139)"><= > > font face=3D"monospace, monospace">Henrique C. > S= > > . Junior
> > Qu=C3=ADmico Industrial - UFRRJ >
> >
style=3D"color:rgb(139,139,139)"><= > > font face=3D"monospace, monospace">Mestrando em Qu=C3=ADmica > > Inorg=C3=A2nica - UFRRJ
> > Centro de Processamento de Dados - PMP
> >
> >
> >
> >
> >
> >
> >
color= > > =3D"#888888"> > >
c= > > olor=3D"#888888"> > >
> > color= > > =3D"#888888"> > > re>--=20 > > James R. Buchwald > > Doctoral Candidate, Theoretical Chemistry > > Dinolfo Laboratory > > Dept. of Chemistry and Chemical Biology > > Rensselaer Polytechnic Institute > > target=3D"_blank">http://www.rpi.edu= > > /~buchwj > >
> > ont color=3D"#888888"> > > > >
color=3D"#888= > > 888">
> > >
> >


--
class= > > =3D"gmail_signature" data-smartmail=3D"gmail_signature">
> > iv>
style=3D"color:rgb(139,139,= > > 139)"> color=3D"#808080">Henriq= > > ue C. S. Junior
Qu=C3=ADmico Industrial - UFRRJ > = > >
face=3D= > > "monospace, monospace">Mestrando em Qu=C3=ADmica Inorg=C3=A2nica - > UFRRJ > >Centro de Processamento de Dados - PMP
>
= > >
> > > > > > --001a113dd29432bd3c053668ae65--> > > --001a114168d673e9020536e564e9 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Hi Dr. Kraemer,

Thanks a lot f= or your help.

Regards,
Swetanshu.

On 30 June 2016 at 18:03, T= obias Kraemer t.kraemer:+:hw.ac.uk <= owner-chemistry__ccl.net> wrote:

Sent to CCL by: "Tobias=C2=A0 Kraemer" [t.kraemer|hw.ac.uk]
Dear Swetanshu,


in your case you are dealing with an overdetermined system of linear
equations, i.e. there are more equations than needed to solve for all
coupling constants (J_ab). You can use the so-called singular value
decompostion (SVD) method to solve for the best set of J_ab. Basically you<= br> consider all your equations resulting from all combinations of spin
configurations (high-spin plus numerous broken-symmetry solutions).
MATLAB can do this job for you, you only have to input the matrices
with the coefficients and J_ab variables, run SVD and you'll have your<= br> result.

I can't find any particular literature on this at the moment, but there= are
plenty of papers on this. This one here by Michl et al. mentions SVD:

Toward (car)boranebased molecular magnetsm Theor. Chem. Acc. (2015) 134:9
Hope this helps


Tobi




Dr. Tobias Kraemer MRSC
Research Associate
Institute of Chemical Sciences
School of Engineering & Physical Sciences
Heriot-Watt University
Edinburgh EH14 4AS
United Kingdom
email: t.kraemer . hw.ac.uk
phone: +44 (0)131 451 3259



>Hi Henrique,
>Thanks again for the advice. I think however, that you were referring t= o
>coming up with different models (each generally having a different numb= er
>of coupling constants) before proceeding with the calculation of coupli= ng
>constants (please correct me if I am wrong). For the system I am studyi= ng,
>I have selected the model. The number of equations I have for calculati= ng
>the coupling constants is much greater than the number of coupling
>constants that I need to calculate. Depending upon the set of equations= I
>choose, I get a different set of J values. Can you please guide me as t= o
>how should I choose the appropriate set of equation for calculating the= J
>values.
>Thanks again,
>Swetanshu.


> "Henrique C. S. Junior henriquecsj~~gmail.com"=C2=A0 wrote= :
>
> Sent to CCL by: "Henrique C. S. Junior" [henriquecsj+*+gmail.com]=
> --001a113dd29432bd3c053668ae65
> Content-Type: text/plain; charset=3DUTF-8
> Content-Transfer-Encoding: quoted-printable
>
> Hi, Swetanshu,
> You don't need the coupling constants before, but you need to perf= orm a
> study to understand what couplings are relevant to your system (to fig= ure
> out how complex the Hamiltonian will be). After you understood your system,
> you can use, as an example, the software DAVE[1] to see if your model<= br> fits
> your experimental data. If not, you have to re-think your system and t= ry
> again to obtain a better fit.
>
> [1] - https://www.ncnr.nist.gov/dave/download.html<= /a>
>
> 2016-06-28 16:53 GMT-03:00 Tandon Swetanshu tandons-,-tcd.ie <
> owner-chemistry.:.ccl.net>:
>
> > Hi Henrique,
> >
> > Thanks a lot for the insight. I have a small doubt. Before obtain= ing
the
> > susceptibility curve, we need to obtain the coupling constant. So= can't
w=3D
> e
> > just compare the calculated coupling constants w= ith the experimental
ones=3D
> ?
> >
> > Thanks again,
> > Swetanshu.
> >
> > On 26 June 2016 at 22:05, Henrique C. S. Junior henriquecsj(~)gmail.com
<
> > owner-chemistry!!ccl.net> wrote:
> >
> >> Hi, Swetanshu,
> >> It is not an easy task to decide what configuration is correc= t to
> >> describe the magnetic couplings in a polynuclear system. The = best
approa=3D
> ch
> >> is to compare the various solutions with an = experimental magnetic
> >> susceptibility curve using a statistical fit software (like o= rigin).
> >>
> >>
> >>
> >> ----------
> >> *Henrique C. S. Junior*
> >> Qu=3DC3=3DADmico Industrial - UFRRJ
> >> Mestrando em Qu=3DC3=3DADmica Inorg=3DC3=3DA2nica - UFRRJ
> >> Centro de Processamento de Dados - PMP
> >>
> >>
> >> ------------------------------
> >> > From: owner-chemistry=3DC3=3D8Cl.net
> >> To: henriquecsjgmail.com
> >> Subject: CCL: Coupling constant (Jab) - Why more unpaired ele= ctrons
mean=3D
> s
> >> a smaller coupling?
> >> Date: Fri, 24 Jun 2016 11:45:36 +0100
> >>
> >> Hi All,
> >>
> >> I have a question somewhat related to this topic. When workin= g out the
J
> >> values in a system with more than 3 metal atoms, there are ma= ny
differen=3D
> t
> >> solutions.=C2=A0 Each solutions is obtained = by choosing a different set of
> >> equations. From the above discussion it seems to me that the = large
> >> differeence in the solutions are due to the large number of u= npaired
> >> electrons and the reduction in the spacing between levels at = higher
ener=3D
> gy.
> >> Due to this, depending upon the states under= consideration the J
values
> >> obtained would differ (please correct me if I am wrong). But = how does
on=3D
> e
> >> decide as to which set of solution is approp= riate.
> >>
> >> Thanks,
> >> Swetanshu.
> >>
> >> On 12 June 2016 at 00:27, James Buchwald buchwja/rpi.edu <
> >> owner-chemistry,ccl.net> wrote:
> >>
> >> Hi Henrique,
> >>
> >> The diminishing Jab that you're predicting assumes that (= E[HS] -
E[BS])
> >> does not grow as quickly as the spin term in the denominator.=
Depending=3D
>=C2=A0 on
> >> the system, this is not necessarily the case, and the energy = spacing
can
> >> grow faster.
> >>
> >> The reason that the equations appear to cause this is that th= e
> >> Heisenberg-Dirac-van Vleck Hamiltonian (which the three equat= ions were
> >> derived from) has a "spin ladder" of solutions rang= ing from the low-
spin=3D
>=C2=A0 to
> >> the high-spin states.=C2=A0 If your low-spin state is a singl= et, you'll
also
> >> have triplets, pentets, and so on until you reach the high-sp= in state.
> >> Similarly, if you start from a doublet, you'll have inter= mediate
quartet=3D
> s,
> >> etc.
> >>
> >> As you introduce more and more unpaired electrons, the spin o= f the
> >> high-spin state increases - but all of the intermediate state= s between
t=3D
> he
> >> high-spin and low-spin limits still exist.= =C2=A0 You can work out the
splitti=3D
> ng
> >> between these individual states in terms of = J, and what ends up
happenin=3D
> g
> >> is that the states spread out.=C2=A0 The den= ominator essentially corrects
for
> >> that spacing, rather than saying anything about the strength = of the
> >> magnetic coupling.
> >>
> >> Best,
> >> James
> >>
> >> On 06/11/2016 05:54 PM, Henrique C. S. Junior henriquecs= j-x-gmail.com
> >> wrote:
> >>
> >> I hope this is not a "homework" question, but I'= ;m having a bad time
> >> trying to figure this out.
> >> Available literature proposes 3 equations to calculate the co= upling
> >> constant during a Broken-Symmetry approach:
> >>
> >> J(1) =3D3D -(E[HS]-E[BS])/Smax**2
> >> J(2) =3D3D -(E[HS]-E[BS])/(Smax*(Smax+1))
> >> J(3) =3D3D -(E[HS]-E[BS])/(<S**2>HS-<S**2>BS)
> >>
> >> I'm intrigued by the fact that, from the equations, the m= ore the
system
> >> have unpaired electrons, the minor will be Jab. Why does this= happen?
> >> Doesn't more unpaired electrons increase magnetic momenta= (and an
increa=3D
> se
> >> in magnetic coupling)?
> >>
> >> --
> >> *Henrique C. S. Junior*
> >> Qu=3DC3=3DADmico Industrial - UFRRJ
> >> Mestrando em Qu=3DC3=3DADmica Inorg=3DC3=3DA2nica - UFRRJ
> >> Centro de Processamento de Dados - PMP
> >>
> >>
> >> --
> >> James R. Buchwald
> >> Doctoral Candidate, Theoretical Chemistry
> >> Dinolfo Laboratory
> >> Dept. of Chemistry and Chemical Biology
> >> Rensselaer Polytechnic Institutehttp://www.rpi.edu/~buchwj
> >>
> >>
> >>
> >
>
>
> --=3D20
> *Henrique C. S. Junior*
> Qu=3DC3=3DADmico Industrial - UFRRJ
> Mestrando em Qu=3DC3=3DADmica Inorg=3DC3=3DA2nica - UFRRJ
> Centro de Processamento de Dados - PMP
>
> --001a113dd29432bd3c053668ae65
> Content-Type: text/html; charset=3DUTF-8
> Content-Transfer-Encoding: quoted-printable
>
> <div dir=3D3D"ltr"><div class=3D3D"gmail_defau= lt" style=3D3D"font-
family:monospac=3D
> e,monospace">Hi,=3DC2=3DA0<span style=3D3D"font-size:1= 2.8px;font-
family:arial,san=3D
> s-serif">Swetanshu,</span></div><div class=3D3D= "gmail_default"
style=3D3D"font-=3D
> family:monospace,monospace"><span style=3D3D"font-size= :12.8px;font-
family:ari=3D
> al,sans-serif">You don&#39;t need the coupling constants b= efore, but you
ne=3D
> ed to perform a study to understand what couplings ar= e relevant to your
sys=3D
> tem (to figure out how complex the Hamiltonian will b= e). After you
understo=3D
> od your system, you can use, as an example, the softw= are DAVE[1] to see
if =3D
> your model fits your experimental data. If not, you h= ave to re-think your
s=3D
> ystem and try again to obtain a better fit.</span></div>&l= t;div
class=3D3D"gmail=3D
> _default" style=3D3D"font-family:monospace,monospace"&g= t;<span style=3D3D"font-
siz=3D
> e:12.8px;font-family:arial,sans-serif"><br></span>= </div><div
class=3D3D"gmail=3D
> _default"><span style=3D3D"font-family:arial,sans-seri= f;font-size:12.8px">
[1]=3D
>=C2=A0 -=3DC2=3DA0</span><span style=3D3D"font-size:12.8p= x"><a
href=3D3D"https://www.ncnr=3D
>
.nist.gov/dave/download.html">htt= ps://www.ncnr.nist.gov/dave/download.html<
=3D
> /a></span></div></div><div class=3D3D"gma= il_extra"><br><div
class=3D3D"gmail_qu=3D
> ote">2016-06-28 16:53 GMT-03:00 Tandon Swetanshu tandons-,-<= ;a
href=3D3D"http:=3D
> //tcd.i= e">tcd.ie</a> <span dir=3D3D"ltr">&lt;<a h= ref=3D3D"mailto:owner-
chemistr=3D
> y.:.cc= l.net" target=3D3D"_blank">owner-chemistry.:.ccl.net</a&= gt;&gt;</span>:
<br><bl=3D
> ockquote class=3D3D"gmail_quote" style=3D3D"margin:0 0 = 0 .8ex;border-left:1px
#=3D
> ccc solid;padding-left:1ex"><div dir=3D3D"ltr">= ;<div><div><div>Hi Henrique,
<br=3D
> ><br></div>Thanks a lot for the insight. I have a small= doubt. Before
obtai=3D
> ning the susceptibility curve, we need to obtain the = coupling constant.
So =3D
> can&#39;t we just compare the calculated coupling constants with t= he
experi=3D
> mental ones? <br><br></div>Thanks again,<br>&l= t;/div>Swetanshu.<br></div>
<div =3D
> class=3D3D"gmail_extra"><br><div class=3D3D"= ;gmail_quote">On 26 June 2016 at
22:=3D
> 05, Henrique C. S. Junior henriquecsj(~)<a href=3D3D"http://gmail.com= "
target=3D
> =3D3D"_blank">gmail.com</a> <span dir=3D3D"ltr&q= uot;>&lt;<a href=3D3D"mailto:owner= -
che=3D
> mistry!!ccl.net" target=3D3D"_blank">owner-chemistry!!ccl.net</= a>&gt;
</span> =3D
> wrote:<br><blockquote class=3D3D"gmail_quote" style= =3D3D"margin:0 0 0
.8ex;bord=3D
> er-left:1px #ccc solid;padding-left:1ex">
>
>
> <div><div dir=3D3D"ltr"><div><font colo= r=3D3D"#444444"><div><font
face=3D3D"Couri=3D
> er New, sans-serif"><span style=3D3D"font-size:15px;li= ne-height:21.3px">Hi,
S=3D
> wetanshu,</span></font></div><div><font fac= e=3D3D"Courier New, sans-serif">
<s=3D
> pan style=3D3D"font-size:15px;line-height:21.3px">It is n= ot an easy task to
d=3D
> ecide what configuration is correct to describe the m= agnetic couplings in
a=3D
>=C2=A0 polynuclear system. The best approach is to com= pare the various
solutions =3D
> with an experimental magnetic susceptibility curve us= ing a statistical
fit =3D
> software (like origin).</span></font></div><div s= tyle=3D3D"font-
size:15px;lin=3D
> e-height:21.3px"><br></div></font><br>= <br><div><font face=3D3D"Courier
New">-=3D
> ---------</font></div><font color=3D3D"#666666&quo= t; face=3D3D"Courier New">
<b>Henri=3D
> que C. S. Junior</b><br></font><div><font c= olor=3D3D"#666666"
face=3D3D"Courier=3D
>=C2=A0 New">Qu=3DC3=3DADmico Industrial - UFRRJ<br>Mestra= ndo em Qu=3DC3=3DADmica
Inorg=3DC3=3D
> =3DA2nica - UFRRJ<br></font></div><div><fon= t color=3D3D"#666666"
face=3D3D"Courie=3D
> r New">Centro de Processamento de Dados - PMP</font><= /div><br><br><div>
<hr>=3D
> &gt; From: owner-chemistry=3DC3=3D8Cl.net<br>To: <a
href=3D3D"http://henriquecsjg=3D
> mail.= com" target=3D3D"_blank">henriquecsjgmail.com&l= t;/a><br>Subject: CCL:
Coupl=3D
> ing constant (Jab) - Why more unpaired electrons mean= s a smaller
coupling?<=3D
> br>Date: Fri, 24 Jun 2016 11:45:36 +0100<br><br><div= dir=3D3D"ltr">Hi All,
<di=3D
> v><br></div><div>I have a question somewhat relat= ed to this topic. When
wor=3D
> king out the J values in a system with more than 3 me= tal atoms, there are
m=3D
> any different solutions.=3DC2=3DA0 Each solutions is obtained by choos= ing a
dif=3D
> ferent set of equations. From the above discussion it= seems to me that
the =3D
> large differeence in the solutions are due to the lar= ge number of
unpaired =3D
> electrons and the reduction in the spacing between le= vels at higher
energy.=3D
>=C2=A0 Due to this, depending upon the states under co= nsideration the J values
ob=3D
> tained would differ (please correct me if I am wrong)= . But how does one
dec=3D
> ide as to which set of solution is appropriate. <br></div>= <div><br></div>
<d=3D
> iv>Thanks,</div><div>Swetanshu.</div><div>&= lt;br><div>On 12 June 2016 at
00:27=3D
> , James Buchwald buchwja/<a href=3D3D"http://rpi.edu"
target=3D3D"_blank">rpi.e=3D
> du</a> <span dir=3D3D"ltr">&lt;<a href=3D= 3D"mailto:owner-chemistry,ccl.net"= ;
tar=3D
> get=3D3D"_blank">owner-chemistry,ccl.net</a>&gt;</s= pan> wrote:<br>
<blockquote=3D
>=C2=A0 style=3D3D"border-left:1px solid rgb(204,204,204);padding-l= eft:1ex">
>=C2=A0 =3D20
>=C2=A0 =C2=A0 =3D20
>=C2=A0 =3D20
>=C2=A0 =C2=A0<div>
>=C2=A0 =C2=A0 =C2=A0Hi Henrique,<br>
>=C2=A0 =C2=A0 =C2=A0<br>
>=C2=A0 =C2=A0 =C2=A0The diminishing Jab that you&#39;re predicting = assumes that (E[HS] -
>=C2=A0 =C2=A0 =C2=A0E[BS]) does not grow as quickly as= the spin term in the
>=C2=A0 =C2=A0 =C2=A0denominator.=3DC2=3DA0 Depending on the syst= em, this is not necessarily
the
>=C2=A0 =C2=A0 =C2=A0case, and the energy spacing can grow faster.<br= >
>=C2=A0 =C2=A0 =C2=A0<br>
>=C2=A0 =C2=A0 =C2=A0The reason that the equations appe= ar to cause this is that the
>=C2=A0 =C2=A0 =C2=A0Heisenberg-Dirac-van Vleck Hamiltonian (which the t= hree equations
>=C2=A0 =C2=A0 =C2=A0were derived from) has a &quot;spin ladd= er&quot; of solutions ranging
f=3D
> rom the
>=C2=A0 =C2=A0 =C2=A0low-spin to the high-spin states.=3DC2=3DA0 If your= low-spin state is a
>=C2=A0 =C2=A0 =C2=A0singlet, you&#39;ll also have triplets, pentets= , and so on until you
>=C2=A0 =C2=A0 =C2=A0reach the high-spin state.=3DC2=3DA0 Similarly, if = you start from a
doublet=3D
> ,
>=C2=A0 =C2=A0 =C2=A0you&#39;ll have intermediate quartets, etc.<= br>
>=C2=A0 =C2=A0 =C2=A0<br>
>=C2=A0 =C2=A0 =C2=A0As you introduce more and more unp= aired electrons, the spin of the
>=C2=A0 =C2=A0 =C2=A0high-spin state increases - but all of the intermed= iate states
>=C2=A0 =C2=A0 =C2=A0between the high-spin and low-spin limits st= ill exist.=3DC2=3DA0 You can
wo=3D
> rk
>=C2=A0 =C2=A0 =C2=A0out the splitting between these in= dividual states in terms of J, and
>=C2=A0 =C2=A0 =C2=A0what ends up happening is that the states sp= read out.=3DC2=3DA0 The
>=C2=A0 =C2=A0 =C2=A0denominator essentially corrects f= or that spacing, rather than
>=C2=A0 =C2=A0 =C2=A0saying anything about the strength of the ma= gnetic coupling.<br>
>=C2=A0 =C2=A0 =C2=A0<br>
>=C2=A0 =C2=A0 =C2=A0Best,<br>
>=C2=A0 =C2=A0 =C2=A0James<span><br>
>=C2=A0 =C2=A0 =C2=A0<br>
>=C2=A0 =C2=A0 =C2=A0<div>On 06/11/2016 05:54 PM, Henrique C. S. >=C2=A0 =C2=A0 =C2=A0 =C2=A0Junior <a href=3D3D"http://henr= iquecsj-x-gmail.com"
target=3D3D"_blank">h=3D
> enriquecsj-x-gmail.com</a> wrote:<br>
>=C2=A0 =C2=A0 =C2=A0</div>
>=C2=A0 =C2=A0 =C2=A0<blockquote>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0<div dir=3D3D"ltr">
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace">I
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0hope this is not= a &quot;homework&quot; question, but
I&#39;m=3D
>=C2=A0 having a
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0bad time trying = to figure this out.</font></div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace">Available
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0literature proposes 3 equations to calculate the coupling
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0constant = during a Broken-Symmetry approach:</font></div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace"><br>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</font></div&g= t;
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace">J(1)
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=3D3D -(E[HS]-E[= BS])/Smax**2</font></div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace">J(2)
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=3D3D -(E[HS]-E[= BS])/(Smax*(Smax+1))</font></div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace">J(3)
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0=3D3D -(E[HS]-E[= BS])/(&lt;S**2&gt;HS-&lt;S**2&gt;BS)</font>
</di=3D
> v>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace"><br>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</font></div&g= t;
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><font face=3D3D&= quot;monospace, monospace">I&#39;m
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0intrigued by the fact that, from the equations, the more
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0the system have = unpaired electrons, the minor will be Jab.
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0Why does = this happen? Doesn&#39;t more unpaired electrons
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2= =A0increase magnetic momenta (and an increase in magnetic
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0coupling)= ?</font></div><span class=3D3D"HOEnZb"><font=
color=3D3D"=3D
> #888888"><span><font color=3D3D"#888888">= ;
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</font></span></font&g= t;</span></div><span class=3D3D"HOEnZb"><fon= t
colo=3D
> r=3D3D"#888888"><span><font color=3D3D"#888= 888">
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div><br>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0-- <br>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div data-smartmail=3D3D"gmai= l_signature">
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div dir=3D3D"ltr"= ;>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div dir=3D3D= "ltr">
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<div&g= t;
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0&l= t;div dir=3D3D"ltr"><span
style=3D3D"color:rgb(139,139,139)"><=3D
> font face=3D3D"monospace, monospace"><b><font co= lor=3D3D"#808080">Henrique C.
S=3D
> . Junior</font></b><br>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0Qu=3DC3=3DADmico Industrial - UFRRJ</font></sp= an>
</div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0&l= t;div dir=3D3D"ltr"><span
style=3D3D"color:rgb(139,139,139)"><=3D
> font face=3D3D"monospace, monospace">Mestrando em Qu=3DC3= =3DADmica
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0Inorg=3DC3=3DA2nica - UFRRJ<br>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0 =C2=A0 =C2=A0Centro de Processamento de Dados - PMP</font><= br>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 = =C2=A0</span></div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</div&= gt;
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0</div>
>=C2=A0 =C2=A0 =C2=A0 =C2=A0</font></span></font></= span></div><span class=3D3D"HOEnZb"><font
color=3D
> =3D3D"#888888"><span><font color=3D3D"#8888= 88">
>=C2=A0 =C2=A0 =C2=A0</font></span></font></span>= ;</blockquote><span class=3D3D"HOEnZb"><font
c=3D
> olor=3D3D"#888888"><span><font color=3D3D"#= 888888">
>=C2=A0 =C2=A0 =C2=A0<br>
>=C2=A0 =C2=A0 =C2=A0</font></span></font></span>= ;</span><span class=3D3D"HOEnZb"><font
color=3D
> =3D3D"#888888"><span><font color=3D3D"#8888= 88"><span><font color=3D3D"#888888">
<p=3D
> re>--=3D20
> James R. Buchwald
> Doctoral Candidate, Theoretical Chemistry
> Dinolfo Laboratory
> Dept. of Chemistry and Chemical Biology
> Rensselaer Polytechnic Institute
> <a href=3D3D"http://www.rpi.edu/~buchwj"
target=3D3D"_blank">http://www.rpi.edu=3D
> /~buchwj</a></pre>
>=C2=A0 =C2=A0</font></span></font></span></f= ont></span></div><span class=3D3D"HOEnZb"> <f=3D
> ont color=3D3D"#888888">
>
> </font></span></blockquote></div><span clas= s=3D3D"HOEnZb"><font
color=3D3D"#888=3D
> 888"><br></font></span></div></div&= gt;</div></div>
</div></div>
> </blockquote></div><br></div>
> </blockquote></div><br><br clear=3D3D"all&qu= ot;><div><br></div>-- <br><div
class=3D
> =3D3D"gmail_signature" data-smartmail=3D3D"gmail_signat= ure"><div dir=3D3D"ltr">
<d=3D
> iv><div dir=3D3D"ltr"><div><div dir=3D3D&q= uot;ltr"><span
style=3D3D"color:rgb(139,139,=3D
> 139)"><font face=3D3D"monospace, monospace">&l= t;b><font
color=3D3D"#808080">Henriq=3D
> ue C. S. Junior</font></b><br>Qu=3DC3=3DADmico Indus= trial - UFRRJ</font>
</span>=3D
> </div><div dir=3D3D"ltr"><span style=3D3D&quo= t;color:rgb(139,139,139)"><font
face=3D3D=3D
> "monospace, monospace">Mestrando em Qu=3DC3=3DADmica Inor= g=3DC3=3DA2nica -
UFRRJ<br=3D
> >Centro de Processamento de Dados - PMP</font><br></= span></div></div>
</div>=3D
> </div></div></div>
> </div>
>
> --001a113dd29432bd3c053668ae65--
>
>



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