Gaussian 98
Overview
Gaussian 98 is designed to model a broad range of
molecular systems under a variety of conditions, performing its computations
starting from the basic laws of quantum mechanics. Theoretical chemists can use
Gaussian 98 to perform basic research in established and emerging areas
of chemical interest. Experimental chemists can use it to study molecules and
reactions of definite or potential interest, including both stable species and
those compounds which are difficult or impossible to observe experimentally
(short-lived intermediates, transition structures and so on).
Gaussian 98 can also predict energies, molecular structures, vibrational
frequencies and numerous molecular properties for systems in the gas phase and
in solution, and it can model both their ground state and excited states.
Chemists can apply these fundamental results to their own investigations, using
Gaussian 98 to explore chemical phenomena like substituent effects,
reaction mechanisms and electronic transitions.
Setup
Gaussian 98 requires that you set or modify several
system environment variables prior to its use:
Variable |
Value |
GAUSS_EXEDIR |
the Gaussian 98 installion directory |
GAUSS_SCRDIR |
the directory to be used for Gaussian 98 scratch files |
LD_LIBRARY_PATH |
the Gaussian 98 installation directory |
Installation directories vary by machine as follows:
IBM SP, RS6KLab, SunLab |
/usr/local/g98 |
LION-XE, LION-XL |
/usr/global/g98 |
For example, if you wanted to run Gaussian 98 on
LION-XL using /tmp as the
Gaussian 98 scratch directory and your shell was
sh or bash, then you would set your
environment with the following commands:
export GAUSS_EXEDIR="/usr/global/g98"
export GAUSS_SCRDIR="/tmp"
export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$GAUSS_EXEDIR"
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In the same situation if your shell was csh or
tcsh, you would set your environment variables with:
setenv GAUSS_EXEDIR /usr/global/g98
setenv GAUSS_SCRDIR /tmp
setenv LD_LIBRARY_PATH "$LD_LIBRARY_PATH:$GAUSS_EXEDIR"
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If you will be extensively using using Gaussian 98, you
may wish to add these settings to your login profile (.bashrc file for bash
shell users, .cshrc file for csh/tcsh users).
Important Note:
Gaussian 98 makes extensive use of temporary disk files.
The proper setting of GAUSS_SCRDIR is critical to good
performance. Local /tmp is strongly recommended for this
setting. Use of /scratch is recommended only if
Gaussian 98 temporary files exceeds several GB of storage.
Usage
Gaussian 98 is started with the command g98.
Examples
To start Gaussian 98 from the command line on an
interactive-use system such as RS6KLab or
SunLab using an input deck named
foo.com you would use a command such as the following:
$GAUSS_EXEDIR/g98 foo.com
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To start Gaussian 98 with an input deck foo.com on
a system such as LION-XE or LION-XL
that uses the PBS queueing system, a
PBS script such as the following would be used:
#PBS -l nodes=1:ppn=1
#PBS -l walltime=0:10:00
#PBS -j oe
# change the current working directory to the directory where
# the input deck foo.com can be found
cd /home/foo/g98
export GAUSS_EXEDIR=/usr/global/g98
export LD_LIBRARY_PATH="$LD_LIBRARY_PATH:$GAUSS_EXEDIR"
export GAUSS_SCRDIR=/tmp
# start g98 with input deck foo.com
$GAUSS_EXEDIR/g98 foo.com
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Additional information on PBS scripts and submitting jobs
to PBS can be found in the appropriate system's User
Guide in the User Guides section of this website.
To start Gaussian 98 with an input deck foo.com on
a system such as the P640 cluster or the
IBM SP that uses the LoadLeveller
queueing system, a script such as the following would be used:
#!/bin/csh -f
# Sample serial LoadLeveler script for running GAUSSIAN jobs.
# @ job_type = serial
# @ class = g98
# @ comment = g98_job
# @ error = err.$(jobid).$(stepid)
# @ output = out.$(jobid).$(stepid)
# @ requirements = (Memory >= 64) && (OpSys == "AIX43")
# @ wall_clock_limit = 3:00:00
# @ queue
# User defined shell variables here
setenv GAUSS_EXEDIR /usr/local/gaussian/g98
setenv GAUSS_SCRDIR /scratch/gaussian_tmp
$GAUSS_EXEDIR/g98 foo.com
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Documentation
Documention on Gaussian 98 can be accessed via the
command:
This assumes that the instructions in the Setup of
this document have been followed.
Please send questions or suggestions about this web page to beatnic@aset.psu.edu
ASET | ITS | Penn State
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