Subject: Re: CCL:freezing atoms in frequency calculations

From: Yohann Moreau <moreau-.at.-lctn.uhp-nancy.fr>
Date: Thu, 27 May 2004 09:31:13 +0200

Dear Kadir,

Gaussian (98 and 03) does that. Just make a frequency job as usual. To freeze a
particular atom, put the flag "-1"
between the atomic type and the geometrical specifications (for a cartesian
input) . If I remember,
the "not frozen" atom must not be the first one.

Here is an example with methanol (non optimized geometry) :

# RHF/STO-3G freq

frequency job

0 1
  C   -1   -1.153515  -.353884   .000000
  H   -1   -2.064398   .242951   .000000
  C   -1     .000000   .524697   .000000
  H   -1   -1.131237  -.982224   .889165
  H   -1   -1.131237  -.982224  -.889165
  O   -1    1.171017  -.242584   .000000
  H   -1    -.022277  1.153036  -.889165
  H   -1    -.022277  1.153036   .889165
  H         1.924381   .331220   .000000

Which lead to 3 frequencies  with a negative one.

Hope this helps.

Yohann

Kadir Diri wrote:

> Dear all,
> I wonder if there is an ab initio code that lets one freeze all atoms
> but one in a large molecule, and calculate the frequency related to the
> atom which was not not frozen, say, like calculating the frequency of a
> single OH stretch in some molecule?
> Thank you in advance!
> kadir
>
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--

               Yohann MOREAU, Doctorant
       Equipe de Chimie et Biochimie Thioriques
               UMR CNRS-UHP 7565 "SRMSC"
          BP 239, F-54506 Vandoeuvre-lhs-Nancy
http://www.lctn.uhp-nancy.fr/Etudiants/Yohann.Moreau.html