Subject: SUMMARY: Normal mode scan

From: Jens Antony <[email-masked]>
Date: Fri, 24 May 2002 14:13:31 +0200

Dear CCL,

here are the answers to my request from last Friday.

Thanks again.

Jens Antony

--
Free University Berlin
Institute for Mathematics II
Arnimallee 2-6
D-14195 Berlin , Germany

-- Request --

Dear CCL,

1) How can I scan a potential energy surface along a vibrational normal
mode with Gaussian or another molecular electronic structure program
automatically ?

2) How can I increase the precision of the normal modes printed with
Gaussian ?

-- Answer 1 --

Hi Jens,

you might try POLYRATE. It is a program
(designed by Prof. Joel Bowman and others) to
calculate vibrational frequencies and more by
going beyond the harmonic oscillator approximation.

Add the HPFREQ option to the FREQ command.
You can find a very thorough documentation of
G98 at:
http://www.gaussian.com/techinfo.htm

Stefan Fau

-- Answer 2 --

>1) How can I scan a potential energy surface along a vibrational normal

I have a very crude fortran program that, when you give it the hpmodes 
output for a mode, will create a multi step g98 input file that scans (and 
computes what you want) along a mode.  It is not automatic, and it is 
rather ugly, but it seems to work for me.  I'd be happy to send you a copy 
if you'ld like.

>2) How can I increase the precision of the normal modes printed with

The hpmodes keyword will do this.

Steve Williams

-- Answer 3 --

>1) How can I scan a potential energy surface along a vibrational normal

G98 claims to be able to do this using freq as an option to IRC, alas that
is not the case.  The gaussian people says that it will work in rev. B.
Please do let me know if you get an answer to this question.

Theis Ivan Soelling

-- Answer 4 --

  The FREQ=HPModes option will print out the normal modes to higher
precision.

  Douglas J. Fox

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