text: The COLUMBUS PROGRAMS maintain a program unique style that distinguish itself from most other quantum chemistry programs.
  The program suite is a collection of a number of programs coded in Fortran, each can be executed independently.  These programs communicate through files.  Perl scripts are provided to prepare input files and to link these programs together to perform common tasks such as single point energy calculation, geometry optimization, normal mode analysis, etc. This style provides very high degree of flexibility which is embraced by advanced users.  The open style allows new components to be added to the program suite with ease.  However, such flexibility also increased the complexity of input file preparation and execution, making it very difficult for new users.