MOLCAS manual:

Next: 8.2 Configuring MOLCAS Up: 8. Installation Previous: 8. Installation


8.1 Prerequisites

8.1.1 Prerequisite hardware

In general, MOLCAS can be built on any hardware that runs under a UNIX operating system. Some of these variants of hardware and software have been tested by us, and you should not have any problems to install MOLCAS on any of these. For other platforms you must, most likely, put some effort into this. In many cases the only effort on your part is setting some compiler flags, paths to system software etc. For a list of the platforms where we have successfully installed MOLCAS see our homepage:

To load the executables resident, sufficient memory is required. In addition, the programs are enabled to allocate work space dynamically. To avoid excessive paging we recommend that your machine should be equipped with at least 2 GB of memory per running application. Note, that MOLCAS will run faster with more memory.

To install MOLCAS you should have about 300 MB of free disk space. To run the verification tests of MOLCAS you should have a scratch disk with up to 1 GB of free disk space, depending on the suite you run. For the ``small'' set about 400 MB will suffice. To perform larger calculations, ample amount of scratch disk space is necessary. The exact amount varies with the type of systems studied, but a general recommendation is at least 4 GB of disk space, per production run.

8.1.2 Prerequisite software

If you obtain the source code of MOLCAS then please make certain that the necessary system software is available. To build MOLCAS you need:

  • A Fortran 77 compiler
  • A Fortran 90 compiler (for some modules)
  • A C compiler
  • The GNU make facility. See URL and navigate to the gnumake page or go directly to .
  • Perl (5.008 or higher)
  • working MPI-2 and/or Global Arrays distribution (for parallel MOLCAS)

To install MOLCAS under MS Windows (98/NT/XP) one should install Cygwin (freeware from RedHat Inc., which can be downloaded from The minimal installation of Cygwin to run MOLCAS includes:

  • check that user name (under Windows) does not contain spaces
  • select a disk, which has enough space fro installation of Cygwin and moclas
  • install Cygwin to the root of selected disk with all defaults
  • run setup again and install the following packages: Devel$\rightarrow$gcc4-fortran, Devel$\rightarrow$make, Devel$\rightarrow$gcc4-gcc, Archive$\rightarrow$sharutils, Utils$\rightarrow$time, Perl$\rightarrow$perl
  • optionally install editors: Editors$\rightarrow$mc, Editors$\rightarrow$vim
  • run cygwin.bat to create Cygwin environment for the user
  • copy MOLCAS tar file into your home directory in Cygwin, and proceed with installation in the same way as under Linux.

Installation of MOLCAS under MacOS requires installation of the Apple Developer Tools (Xcode) and a Fortran compiler. These programs could be downloaded from:

However, if you are looking for an out of the box solution, you can download a Free PGI for Mac OS X distribution available at

Graphical User Interface codes in MOLCAS requires an additional system software, including OpenGL and glut library. However, in most of the cases there is no need to install these libraries, since executables for GUI are included into the distribution, or they can be downloaded from MOLCAS webpage (

8.1.3 Preparing the installation

In order to install MOLCAS you need to choose a directory where MOLCAS driver is to be installed. Driver is a small script (created during the installation), which executes scripts and programs form the MOLCAS package and it must be located in any directory included into the PATH.

Driver script molcas uses the value of the environment variable MOLCAS to identify which version to use. The major advantage with this mechanism is that it is easy to switch between different versions of MOLCAS by simply changing the environment variable MOLCAS. However if the current directory is a subdirectory (up to 3-rd level) of MOLCAS tree, this version will be used.

MOLCAS itself can be located in any place on the disk. The installation can be done by root, or by unprivileged user. In the later case you can copy molcas driver script to an appropriate location, e.g. /usr/local/bin after the installation.

All files are contained in a tar archive file with the name molcas81.tar.gz, you need to uncompress the file with the command gunzip molcas81.tar.gz, and untar the package with tar -xvf molcas81.tar.

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Next: 8.2 Configuring MOLCAS Up: 8. Installation Previous: 8. Installation