From owner-chemistry@ccl.net Wed Dec 16 01:10:01 2015 From: "Aniruddha Ganguly ani.physichem-x-gmail.com" To: CCL Subject: CCL:G: how to freeze in gaussian Message-Id: <-51922-151216010853-25317-7b8yjITgBp86y41Sn+EZEw^^server.ccl.net> X-Original-From: Aniruddha Ganguly Content-Type: multipart/alternative; boundary=001a11491bb248bd630526fdbdbe Date: Wed, 16 Dec 2015 11:38:47 +0530 MIME-Version: 1.0 Sent to CCL by: Aniruddha Ganguly [ani.physichem|a|gmail.com] --001a11491bb248bd630526fdbdbe Content-Type: text/plain; charset=UTF-8 If you are trying to freeze a bond length, the simplest option would be to use the letter "F" after the particular bond length in the variable portion, say for example b4= x.xxx F Thus, that particular length will freeze during the calculation. But, in that case you will have to change the "Opt" keyword with "Popt" (partial optimization). I hope it helps. Regards, Aniruddha *Aniruddha Ganguly* *c/o Prof. Nikhil Guchhait* *Senior Research Fellow* *Department of Chemistry* *University of Calcutta* *92, A.P.C. Road* *Kolkata-700009* On Wed, Dec 16, 2015 at 5:15 AM, Sofia Vasilakaki svasilak(-)chem.uoa.gr < owner-chemistry=ccl.net> wrote: > > Sent to CCL by: "Sofia Vasilakaki" [svasilak%a%chem.uoa.gr] > Hi, > > There are a few things you might want to try. Usually 'nosymm' keyword > will keep the atoms fixed during opt. 'modredundant' usually works for me. > There are some examples here http://www.gaussian.com/g_tech/g_ur/k_opt.htm > (scroll down) in case you haven't seen them. > > Here http://www.ccl.net/chemistry/resources/messages/2004/06/02.007-dir/ > is an older thread. > > > Cheers, > Sofia V. > > > > > > > Sent to CCL by: "kiran k" [kd2f..mtmail.mtsu.edu] > > Dear CCLusers, > > > > Could anyone suggest how to find interaction energy between formaldehyde > > and > > fluoride ion in gaussian using z-matrix, by keeping the distance > constant. > > After the calculation, the distance changed. Here is my example input > look > > like > > ---------------------------------------------------------------------- > > #P B3LYP/6-31+G* opt Test > > > > Geometry Optimization > > > > -1 1 > > C > > O 1 r2 > > F 1 r3 2 a3 > > H 1 r4 2 a4 3 d4 > > H 1 r5 2 a5 3 d5 > > Variables: > > r2= 1.2246 > > a3= 90.00 > > r4= 1.1017 > > a4= 122.24 > > d4= 354.18 > > r5= 1.1017 > > a5= 122.24 > > d5= 174.18 > > constant: > > r3= 2.5000 > > > > Thank you in advance> > > --001a11491bb248bd630526fdbdbe Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
If you are trying to freeze a bond length, the simplest op= tion would be to use the letter "F" after the particular bond len= gth in the variable portion, say for example

b4=3D x.xxx= F

Thus, that particular length will freeze during= the calculation.

But, in that case you will have = to change the "Opt" keyword with "Popt" (partial optimi= zation).

I hope it helps.

Regards,
Aniruddha

Aniruddha Ganguly
c/o Prof. Nikhil G= uchhait
Seni= or Research Fellow
Department of Chemistry
University of Calcutta
92, A.P.C. Road
Kolkata-700009

On Wed, Dec 16, 2015 at 5:15 AM, Sofia Vasil= akaki svasilak(-)chem.uoa.gr <o= wner-chemistry=ccl.net> wrote:

Sent to CCL by: "Sofia Vasilakaki" [svasilak%a%chem.uoa.gr]
Hi,

There are a few things you might want to try. Usually 'nosymm' keyw= ord
will keep the atoms fixed during opt. 'modredundant' usually works = for me.
There are some examples here http://www.gaussian.com/g_= tech/g_ur/k_opt.htm
(scroll down) in case you haven't seen them.

Here http://www.ccl.net/chemistry= /resources/messages/2004/06/02.007-dir/
is an older thread.


Cheers,
Sofia V.



>
> Sent to CCL by: "kiran=C2=A0 k" [kd2f..mtmail.mtsu.edu]
> Dear CCLusers,
>
> Could anyone suggest how to find interaction energy between formaldehy= de
> and
> fluoride ion in gaussian using z-matrix, by keeping the distance const= ant.
> After the calculation, the distance changed. Here is my example input = look
> like
>=C2=A0 ----------------------------------------------------------------= ------
> #P B3LYP/6-31+G* opt Test
>
> Geometry Optimization
>
> -1 1
> C
> O=C2=A0 1=C2=A0 r2
> F=C2=A0 1=C2=A0 r3=C2=A0 2=C2=A0 a3
> H=C2=A0 1=C2=A0 r4=C2=A0 2=C2=A0 a4=C2=A0 3=C2=A0 d4
> H=C2=A0 1=C2=A0 r5=C2=A0 2=C2=A0 a5=C2=A0 3=C2=A0 d5
> Variables:
> r2=3D 1.2246
> a3=3D=C2=A0 90.00
> r4=3D 1.1017
> a4=3D 122.24
> d4=3D 354.18
> r5=3D 1.1017
> a5=3D 122.24
> d5=3D 174.18
> constant:
> r3=3D 2.5000
>
> Thank you in advance>
>
>



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