Preparing to Developing New PSI3 Code

Given the complexity of the PSI3 package, the prospect of adding new modules or libraries may seem daunting at first. Let's assume you want to begin writing a new module named great_code for PSI3. The following series of steps will generate the proper directories and Makefiles to get started. For convenience, the top-level directory of the programmer's PSI3 source tree will be referred to as $PSI3 and the top-level directory of the compilation area as $prefix:

1. Generate the new directory in the source tree:
   mkdir $PSI3/src/bin/great_code

2. cd $PSI3/src/bin/great_code

3. Copy an existing Makefile.in from another module:
   cp ../cscf/Makefile.in .

4. Edit the Makefile.in so that it lists only the source files for great_code and includes in PSILIBS only those libraries needed to link the executable.

5. Return to the top of the source tree: cd $PSI3

6. Add the name of great_code's Makefile to configure.in (near the bottom of the file) and run autoconf to generate a new configure script.

7. Go to the top of the compilation tree: cd $prefix.

8. Re-run the configure script to generate the Makefile for great_code. Make sure you use the same options to configure that you used before or other Makefile's may not function properly. The command you used before can be found in $prefix/config.status. (See also the PSI3 installation manual for more details on the options to configure.)

Now you are ready to work on the code. Changes to source files (including the Makefile should be made to the files in $PSI3/src/bin/great_code and all compilations should be run in $prefix/src/bin/great_code.