Subject: frequencies vs. coordinates

From: "Paneth" <[email-masked]>
Date: Tue, 23 Nov 1999 17:54:58 +0100

> Dear all:
> I have a question regarding frequency calculations in G98. Depending on
> what's taken from the checkpoint, redundant internal or cartesian
> coordinates the normal vibrations are somewhat different. Unfortunately,
the
> isotopic differences are so large that the isotope effects are not
reliable.
> Below I give an abbreviated version - full output files are attached.

my original posting turned out to be too large for automatic distribution so
the abovementioned files are zipped!

> The question is which set should be trusted:
>
> 1st set:
> .....
> #RHF 6-31++G** freq=(readisotopes,readfc) geom=check
>  ----------------------------------------------------
>  1/29=2,38=1/1;
>  2//2;
>  7/8=2,25=11/16;
>  99/5=2/99;
>  ------------
>  comment line
>  ------------
>  No Z-matrix found on checkpoint file.
>  Cartesian coordinates read from the checkpoint file:
> .......
>  Frequencies --   277.4024               357.4032               714.2104
>
> 2nd set:
> .....
>  Redundant internal coordinates taken from checkpointfile:
> ............
> Frequencies --   278.9392               357.7119               701.2824
> ---------
> Cheers, Piotr

******************************************************
Professor Piotr Paneth
Department of Chemistry, Technical University
Zeromskiego 116, 90-924 Lodz, Poland
phone/fax: (+48 42) 631-3199      fax: (+48 42) 636-5008