Development note
	Development of this chapter has been postponed.

In the following three chapters, we will discuss a few of the ab initio quantum chemistry packages that are available. Some of the packages are open source and encourage collaborative efforts with outside users and other commercial packages can cost thousands of dollars, and the source code is not available to the user. In selecting a package to review we will first consider three criteria:

Whether a software package has the capabilities we need depends on what problem we are trying to address, which we will discuss later. The second criterion, in the present case, requires that the package be free of charge and it must be able to run on a Pentium II 266 MHz with 224 Mbytes of RAM and about 200 Mbytes of hard disk space (left). To satisfy the third criterion we would prefer a software package released under the GNU Public License or with as few restrictions as possible to allow us to change the software as required to solve a given problem. The list shown below is not exhaustive and descriptions of other packages can be found at NetSci.org, OpenScience.org, and the Computer Physics Communications Program Library, Quantum Chemistry Program Exchange, Computational Chemistry List, Scientific Applications on Linux, and other Web sites.

Many of these packages including octopus and ABINIT are written in Fortran 90/95 so those who wish to do development work and are used to using the GNU g77 compiler will need to find alternatives. Fortunately, for Intel platforms, the Intel Fortran Compiler 7.1 is freely available for noncommerial use. It can be obtained at http://www.intel.com/software/products/compilers/. The list of compiler options can be viewed at http://www.intel.com/software/products/compilers/flin/docs/f_qrg/qck_alpha.htm. As an example, the options that could be used for our antiquated Pentium II system are shown in the table below.