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Contents

Introduction

"Gaussian 03 is the latest in the Gaussian series of electronic structure programs. Gaussian 03 is used by chemists, chemical engineers, biochemists, physicists and others for research in established and emerging areas of chemical interest. Starting from the basic laws of quantum mechanics, Gaussian predicts the energies, molecular structures, and vibrational frequencies of molecular systems, along with numerous molecular properties derived from these basic computation types. It can be used to study molecules and reactions under a wide range of conditions, including both stable species and compounds which are difficult or impossible to observe experimentally such as short-lived intermediates and transition structures. This article introduces several of its new and enhanced features. "

Version and availability

Gaussian is a commercial software so users from an institution which has a Gaussian license can use Gaussian on the LONI system deployed at that institution. Gaussian 03 is available on Bluedawg, Ducky and Zeke, but TCP Linda is only available on Bluedawg and Zeke due to license limitation. LaTech and ULL users can run Gaussian in either distributed (using Linda) or shared memory mode on Bluedawg and Zeke, while Tulane users can use Gaussian 03 in shared memory mode using up to 8 processors on Ducky.

Usage

Before using Gaussian, you need to set up your environment, which can be done using Softenv. If you are using SoftEnv to manage your environment, you can use Gaussian by adding "+gaussian-03" to your ~/.soft file and doing "resoft" to reset to your environment:

$ vi .soft
  #
  # This is your SoftEnv configuration run control file.
  #
  #   It is used to tell SoftEnv how to customize your environment by
  #   setting up variables such as PATH and MANPATH.  To learn more
  #   about this file, do a "man softenv".
  #
  @default
  #To use Gaussian03
  +gaussian-03
$ resoft

If you want to run Gaussian in shared memory mode, add the following line at the top of your input file:

   %NProcShared=<number of processors>

If you want to run Gaussian in distributed memory mode, add the following line at the top of your input file:

   %NProcLinda=<number of processors>

Or, you can combine the two (assuming you want to run the job on 4 nodes with 32 processors):

   %NProcLinda=4
   %NProcShared=8

To submit a Gaussian job, you can use the runG03 command:

   runG03 <inputfile> <nprocs> <queue> <tasks>

where <inputfile> is the name of the input file, <nprocs> is the total number of processors (e.g. 32 for the input file above), <queue> is the name of queue, and <tasks> is the maximum number of processors on each node. The <tasks> option is optional and the default value of 8 will be assumed if it is omitted on the command line. The runG03 command will automatically generate a LoadLeveler script, which you can use as a template to submit other Gaussian jobs.

Troubleshooting

Problem: the job dies without any error message but there're warnings like "Warning!!: The largest alpha MO coefficient is xxxxDxxx" in the log file.

From the CCL (computational chemist list):
 
This is caused by collinearity in the overlap matrix.  There are basis
functions that are too similar, and when the overlap matrix is diagonalized
there a re eigenvalues that are too close to being zero, and this leads to
large values when the inverse square roots are taken of the eigenvalues in
the process of computing the necessary S**(-1/2) matrix, which is then used
in computing the MO's in the original non-orthogonal basis set.  This
problem can be minimized by using smaller basis sets.  There are no magic
formulas to predict this problem other than the lowest eigenvalue of the
overlap matrix which is probably printed in the output.
Perhaps start with 6-311G++ and add basis functions in steps and check on
the lowest overlap eigenvalue.
  
The original message

References

For common Gaussian problems please see, https://docs.loni.org/wiki/Gaussian_Common_Problems

Gaussian 03 online manual: http://www.gaussian.com/g_ur/g03mantop.htm

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