Thanks to reply Dr. Joshua Layfield. your Z-Matrix of H2-Fe(OH= )3 was very useful for me. I used DFT (B3LYP and B3PW91) method and some ba= sis set, also I used the same kayword that you used it in rout section "POPT(z-matrix)"= , but there is problem in results, they were not as expected. I can not wha= t is the reason. Can you advice me about any additional kaywords to get bet= ter results?

Thank you anothe= r

Safiya Amer

Graduate student

=D9=85=D9=86: "Layfield, Joshua P= . jlayfield**stthomas.edu" <owner-chemistry]![ccl.net>
=D8=A5=D9=84=D9=89: "Amer, Safiya Ess = " <amersaf85]![yahoo.com>
=D8=AA=D8=A7=D8=B1=D9=8A=D8=AE =D8=A7=D9=84=D8=A5=D8=B1=D8=B3=D8= =A7=D9=84: =D8=A7=D9=84=D8=A3=D8=B1=D8=A8=D8=B9=D8=A7=D8=A1 25 = =D9=85=D8=A7=D8=B1=D8=B3=D8=8C 2015=E2=80=8F 12:21 =D8=B5
=D8=A7=D9=84=D9=85=D9=88=D8=B6=D9=88=D8=B9: CCL:G: Ghost atoms (symbol Bq)

Sent to CCL by: "Layfield, Joshua P." [jlayfie= ld _ stthomas.edu]

Safiya,

&= nbsp; If you want to do a partially optimized scan something like this shou= ld

work.&n= bsp; (Please note that my method and geometry are not great). By
<= /div>

defining the t= wo hydrogen positions relative to the the dummy atom (xx)

you can scan the h2 molecul= e as a unit. Also, if you want to do a frozen

scan you also freeze the addition= al degrees of freedom at a good geometry

by adding the =C2=B3F=C2=B2 flag. Hope= this helps!

#HF/6-31G = POPT(z-matrix)

Scanning the intermolecular distance between= Fe(OH)3 and H2

1 1

o 1 ofe2

o &nb= sp; 1 ofe3 2 ofeo3

o 1 ofe4 &n= bsp; 2 ofeo4 3 dih4

xx 1 xxfe5 = 2 xxfeo5 3 dih5

h 2 ho6 = 1 hofe6 3 dih6

h 3 h= o7 1 hofe7 2 dih7

h &n= bsp; 4 ho8 1 hofe8 = 2 dih8

h&= nbsp; 5 hxx9 1 hxxfe9 = 2 dih9

h 5 hxx10 1 hxxfe10 9 dih10

ofe2 2.371600

ofe3 2.371600

ofeo3 = 109.471

ofe4 2.371600

ofeo4 109.471

dih4 120.000

xxfe5 &nb= sp; 2.000000 S 19 0.05

xxfeo5 109.471

dih5 -= 120.000

ho= 6 0.947000

hofe6 109.471

dih6 180.000

ho7 0.947000

ho= fe7 109.471

dih7 0.000

ho8 = 0.947000

hofe8 = 109.471

dih8 -180.000
<= /div>

hxx9 &nb= sp; 0.370000 f

hxxfe9 90.000 f

dih9 = ; 180.000 f

hxx10 0.370000 f

hxxfe10 90.0= 00 f

dih10 180.000 f

<= /div>

Dr. Joshua Lay= field

Assi= stant Professor, Department of Chemistry

University of St. Thomas

Maill # OSS 402

2115 Summit Ave.
=

St. Paul, MN = 55105-1079

(651) 962-5577

On 3/24/15, 12:00 PM, "Safiya Ess Amer amersaf85]~[= yahoo.com"

<owner-chemistry]*[ccl.net> wrote:

>Sent to CCL by: "Safiya Ess Amer" [amersaf85||yahoo.c= om]

>Hello.

>Plea= se, how can I use ghost atom with Cartesian coordinates?

>I have system of H2-Fe(OH)3 and use G03W for getting energy as= function

= >of

>more distances (Z) from center = of H2 to Fe atom. I am calculating now

>each

>value = of energy at some distance manually. I need to put ghost atom at

<= div dir=3D"ltr" id=3D"yui_3_16_0_1_1428501633350_5667">>center

>of H2, how can= I do that to get PES.

>Can anyone help me in input file?

>I have geometry of the system.
=

>Thanks in adva= nce

><= br>

>Safiya Amer

>ame= rsaf85]^[yahoo.com>

-=3D This is automatically added to each message by the maili= ng script =3D-

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------=_Part_2658080_1212069801.1428507928881-- From owner-chemistry@ccl.net Wed Apr 8 12:36:01 2015 From: "=?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal victor_+_fluor.quimica.uniovi.es" To: CCL Subject: CCL:G: Understanding restricted vs unrestricted calculations Message-Id: <-51225-150408121644-11129-aCQCErtSYsEkiztLycb2MA~~server.ccl.net> X-Original-From: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal Content-disposition: inline Content-transfer-encoding: 8BIT Content-type: text/plain; charset=iso-8859-1 Date: Wed, 08 Apr 2015 18:10:22 +0200 MIME-version: 1.0 Sent to CCL by: =?iso-8859-1?Q?V=EDctor_Lua=F1a?= Cabal [victor~~fluor.quimica.uniovi.es] On Wed, Apr 08, 2015 at 04:23:37PM +0200, ashika torikora ashika.torikora(_)gmail.com wrote: > Hello everyone, > > I am trying to understand the difference between restricted and > unrestricted calculations. So far I have somewhat understood the basic > difference (in restricted calculations consider the calculation is > restricted to having two electrons per occupied orbital whereas for > unrestricted calculations there are two complete sets of orbitals, one for > the alpha electrons and one for the beta electrons). > My question is more of a practical one. > When should one use an unrestricted calculation? > When is restricted or unrestricted used by default in gaussian(09) and when > should one specify it? There are many answers. The simplest is: in a restricted calculation the orbital description of alpha and beta spin electrons are forced to be equivalent. in an unrestricted calculation that equivalence is not enforced The difference between electron density of alpha and beta electrons produces information on the magnetism of the system, mainly but not only. There are other workers in this list that can provide a more complex and detailed answer. Best regards, Dr. V�ctor Lua�a -- . . DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy: / `' \ "I think the problem, to be quite honest with you, /(o)(o)\ is that you have never actually known what the question is." /`. \/ .'\ / '`'` \ "Lo mediocre es peor que lo bueno, pero tambi�n es peor | \'`'`/ | que lo malo, porque la mediocridad no es un grado, es una | |'`'`| | actitud" \/`'`'`'\/ -- Jorge Wasenberg, 2015 ===(((==)))==================================+========================= ! Dr.V�ctor Lua�a ! Mediocre is worse than ! Departamento de Qu�mica F�sica y Anal�tica ! good, but it is also ! Universidad de Oviedo, 33006-Oviedo, Spain ! worse than bad, because ! e-mail: victor~~fluor.quimica.uniovi.es ! mediocrity is not a grade, ! phone: +34-985-103491 fax: +34-985-103125 ! it is an attitude +--------------------------------------------+ GroupPage : http://azufre.quimica.uniovi.es/ (being reworked) From owner-chemistry@ccl.net Wed Apr 8 13:11:00 2015 From: "Yingbin Ge yingbin.ge|-|gmail.com" To: CCL Subject: CCL:G: Understanding restricted vs unrestricted calculations Message-Id: <-51226-150408120627-7488-WH7Wy0qVOtcaqKHrypIjew~!~server.ccl.net> X-Original-From: Yingbin Ge Content-Type: multipart/alternative; boundary=001a113560183193c10513389993 Date: Wed, 8 Apr 2015 08:58:12 -0700 MIME-Version: 1.0 Sent to CCL by: Yingbin Ge [yingbin.ge]^[gmail.com] --001a113560183193c10513389993 Content-Type: text/plain; charset=UTF-8 Dear Ashika, When should one use an unrestricted calculation? A: when you suspect there is at least one spatial orbital that is occupied by 1 electron and you do not wish to do a restricted open-shell (RO) calculation. For example, Na, Mg+, the ground electronic state of Sc, Ti, V, Cr, Mn and most other transition metal atoms, the ground electronic state of O2, a molecule with a severely stretched bond, etc. When is restricted or unrestricted used by default in gaussian(09) and when should one specify it? I think the default is restricted whenever the system has an even number of electrons. But I always examine and change it if necessary. Sincerely, Yingbin -- Yingbin Ge, Associate Professor Science Building 207A Department of Chemistry Central Washington University 400 E University Way Ellensburg, WA 98926 Office Phone: 509-963-2817 Email: yingbin . cwu.edu --001a113560183193c10513389993 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

Dear Ashika,

When should one use an unrestricted calculation?

A:= when you suspect there is at least one spatial orbital that is occupied by= 1 electron and you do not wish to do a restricted open-shell (RO) calculat= ion. For example,

Na,
Mg+,
the ground electronic stat= e of Sc, Ti, V, Cr, Mn and most other transition metal atoms,
the groun= d electronic state of O2,
a molecule with a severely stretched bond, etc.

When is restricted or unrestricted = used by default in gaussian(09) and when should one specify it?

I think the default is restricted whenever the system has an even number= of electrons. But I always examine and change it if necessary.

Sincerely,

Yingbin

Yingbin Ge, A= ssociate Professor
Science Building 207A
Department of Chemistry
Central Washington University
400 E University Way
Ellensburg, WA 98926
Office Phone: 509-963-2817

Email: yingbin . cwu.edu

--001a113560183193c10513389993-- From owner-chemistry@ccl.net Wed Apr 8 13:45:01 2015 From: "Igors Mihailovs igors.mihailovs0!^!gmail.com" To: CCL Subject: CCL:G: Understanding restricted vs unrestricted calculations Message-Id: <-51227-150408130922-7867-bCIx+G3ltLy1bhp6NBoEIA*o*server.ccl.net> X-Original-From: Igors Mihailovs Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Date: Wed, 8 Apr 2015 20:09:15 +0300 MIME-Version: 1.0 Sent to CCL by: Igors Mihailovs [igors.mihailovs0/a\gmail.com] Hello Ashika, UNrestricted calculations are used for systems with odd number of electrons (free radicals, in particular radical cations and anions that occur upon ionization of a molecule / electron capture by it) and also for systems that have even number of electrons but unpaired: these are biradicals, e. g., oxygen molecule, or, most commonly, these are electronically excited species - singlet and triplet states. All this correspond to spin multiplicity of specie beig higher than 1. By default, Gaussian 09 sets calculation type to be unrestricted only if spin multiplicity is higher than one. However, the initial guess still has alpha and beta states coinciding in energy, so the optimization might not break the spin symmetry by its own, and the resulting wavefuction will be something like a "saddle point" between two unrestricted functions. Spin symmetry means that there is no biradical character of the full wavefunction of Your system, e.g., that alpha and beta electrons are distributed equally – in fact, sharing spatial parts of their wavefunctions, as in restricted calculation. To check if Your unrestricted wavefunction is really unrestricted, You ought to run the same calculation with "Stable=Opt" keyword. This requires a bit more resources than plain single point, as it have to diagonalize configuration interaction (CI) matrices. Personally I appeared at questioning about this when I noticed that values for closed-shell molecules in my unrestricted calculations (not only Kohn–Sham, but even Hartree–Fock) were surprisingly equal to 0.000, with no spin contamination. The last one is "the beast" of unrestricted calculations: those wavefunctions that we obtain by solving Schroedinger equation are not neccessarily eigenfunctions of spin-squared operator, S**2, but in reality they should be; so, in fact unrestricted wavefunction contain some spurious contribution from energetically higher-laying states with greater spin than we have set up in the calculation parameters (electronically "more excited" states). This means that we have somewhat incorrect wavefunction and, as a concequence, somewhat incorrect energy. Spin contamination is usually relatively high for Hartree–Fock and correlated methods (MPn, etc.) based upon it, but particularily less for unrestricted Kohn–Sham DFT calculations. There is one more alternative: restricted open-shell calculations (RO). Here, all spatial shells that in the reality contain two electrons (usually inner shells) are forced to stay together, as in restricted calculation, whereas those containing only one electron are computed as they are. This method should give more reasonable results, but it requires more computational resources, because we now have not only one Slater determinant as in unrestricted calculation, double that of restricted one, but several (multiple) determinants, a bit like in CI. Hope this will be useful, Igors Mihailovs (engineer) Institute of Solid State Physics University of Latvia 2015-04-08 17:23 GMT+03:00, ashika torikora ashika.torikora(_)gmail.com : > Hello everyone, > > I am trying to understand the difference between restricted and > unrestricted calculations. So far I have somewhat understood the basic > difference (in restricted calculations consider the calculation is > restricted to having two electrons per occupied orbital whereas for > unrestricted calculations there are two complete sets of orbitals, one for > the alpha electrons and one for the beta electrons). > My question is more of a practical one. > When should one use an unrestricted calculation? > When is restricted or unrestricted used by default in gaussian(09) and when > should one specify it? > > All answers welcome, > ( ´ ▽ ` )ﾉ >