Gaussian 03 on Sweetgum and Mimosa

The normal Gaussian 03 and 98 are installed on sweetgum and the Linda-enabled Gaussian 03 is installed on mimosa.

Gaussian 03 Online Manual

Efficiency Considerations with Gaussian 03

• Hartree-Fock energies, geometry optimizations and vibrational frequency calculations. Hartree-Fock theory is the base-level electronic structure method: it is the least computationally intensive and is applicable to the widest range of problem types. It is also frequently used as a starting point for more accurate calculations.

• Density functional theory (DFT) energies, geometry optimization and vibrational frequency calculations, using either pure or hybrid functionals. These methods provide additional accuracy over Hartree-Fock theory for many molecular systems by including some of the effects of electron correlationthe way that individual electrons instantaneously affect one anotherneglected by the less expensive method.

• MP2 single point energy calculations and geometry optimizations. MP2 theory is another method which attempts to address the neglect of electron correlation of Hartree-Fock theory, doing so via Møller-Plesset perturbation theory. It is more expensive than Density Functional Theory but is more extensively calibrated than the DFT methods and performs well for some types of molecular systems with which they have trouble.

Note: CCSD problems are not sufficiently parallelizable to approach linear speed-up, and should not be run across multiple cluster nodes.

For most jobs, running 2 processors has the best speedup and performance. For MP2 jobs, you might want to use 6 processors.  This job naturally separates into a series of 6 batches of integral computations. Remember, the more processors you use, the more overhead you get.

To run a Gaussian 98 job on sweetgum, please use this command or edit your own PBS script:

g98sub [-t time] [-m memory] jobs

To run a Gaussian 03 job on sweetgum, please see the June 2003 Parallel-O-Gram article about setting up your enviroment, then use this command or edit your own PBS script:

g03sub [-t time] [-n nproc] [-m memory] input_file

To run a Gaussian 03 job on mimosa: First, make sure that the you have a file called .cshrc in your home directory, and that it contains at least the following line:
setenv g03root /usr/local/apps


Then, please use the g03sub script located in the /usr/local/apps/bin directory. To submit the job, please type:

g03sub [-t time] [-n nproc] [-m memory] input_file

If you need to run a 2 node job with input file as test100.com, the command line will be:

g03sub -n 2 test100.com

If you need to run a 1 node job with input file as test100.com, the command line will be:

g03sub -n 1 test100.com

In your input file, please insert two lines denoting the number of processors (or nodes, in this case) that the job will run on, and the amount of memory it will require. The nprocl value should be the same as the command-line parameter you use to invoke g03sub. For instance, to run your job on two nodes and use 200MB of memory per node, you would add the following two lines:

%nprocl=2

%mem=200MB

If you have any questions about running Gaussian 03 jobs, please contact assist@mcsr.olemiss.edu