The ORCA Quantum Chemistry Program


ORCA is a free quantum chemistry software written by Prof. Frank Neese and cowokers. It has almost all the capabilities that are present in GAUSSIAN, GAMESS and NWChem. You can find the more info about ORCA at

This can also be run on PC’s and Laptops.

Check  the configuration of your Linux PC using

“uname -p ” command  if the answer is

i686 (download 32bit ) or i686 (download 64bit) from  by filling in the form

To run ORCA you need to have openmpi1.4.5 in your system so first install it as explained below (this is given in ORCA forums thanks to Reuti)

  •  tar xf openmpi-1.4.5.tar.gz
  •  mkdir my_openmpi
  •  cd my_openmpi
  •  ../openmpi-1.4.5/configure –prefix=$HOME/local/openmpi-1.4.5_gcc
  •  make
  • make install

Now Download ORCA  and

  • mkdir software
  • mv orca_2_9_1_linux_i686 software/
  • tar xf orca_2_9_1_linux_i686

After doing this go to home and add the following lines in .bashrc

  • export PATH=$HOME/local/openmpi-1.4.5_gcc/bin:$PATH
  • export LD_LIBRARY_PATH=$HOME/local/openmpi-.4.5_gcc/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
  • alias orcaqm=’$HOME/software/orca_2_9_1_linux_i686/orca’

close the .bashrc file and do “exec bash”now test whether code is working or not by running following input file

%pal nprocs 8 end
 %MaxCore 3000
 ! RHF TightSCF PModel

* xyz 0 1
 C 0.000000 0.000000 0.000000
 C 0.000000 0.000000 1.400000
 C 1.212436 0.000000 2.100000
 C 2.424871 0.000000 1.400000
 C 2.424871 0.000000 0.000000
 C 1.212436 0.000000 -0.700000
 H -0.943102 0.000000 1.944500
 H 1.212436 0.000000 3.189000
 H 3.367973 0.000000 1.944500
 H 3.367973 0.000000 -0.544500
 H 1.212436 0.000000 -1.789000
 H -0.943102 0.000000 -0.544500

It runs very smoothly. Submit a job and go for a tea :)This procedure worked for me on my Lappy(Ubuntu), PC (Fedora) and on a small work station. If you have any problems leave a comment.



9 thoughts on “The ORCA Quantum Chemistry Program

  1. Hello;

    I have openSUSE 12.1 (x86_64) OS. First I install openmpi-1.6.4_gcc and tried to run ORCA as you mentioned. It gives an error like this:

    orca_2_9_1_linux_x86-64/orca_gtoint_mpi: error while loading shared libraries: cannot open shared object file: No such file or directory

    Then I look up the directory which contains library files of openmpi. There is file but not exist. After this I install 1.4.5 version of openmpi. This version have correct libmpi_cxx file. I include the PATH and LD_LIBRARY_PATH to .bashrc however it gives the same error.

    Do you have any idea what would be cause the problem and what to do correct?

    Thank you.

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  3. marques pal says:


    I tries to install open mpi 1.4.5, I executed the ./configure command, but when I try to execute the command make/ make install “”make: *** No rule to make target `all’. Stop.”
    message appears, I am new to ubuntu. Please help me in solving the issue

  4. Serindipies says:

    I am trying to use Orca_3.0 in parallel. I have a running version of MPI_1.6.5 but the program dies with:

    mpirun was unable to launch the specified application as it could not access or execute an executable:

    Executable: /orca_gtoint_mpi
    Node: my-user

    while attempting to start process rank 0.
    ORCA finished by error termination in ORCA_GTOInt

    But the following website solved my problem:

  5. Srimanta Pakhira says:

    I followed your steps and I have CentOS (x86_64) OS. First I install openmpi-1.5.4_gcc and tried to run ORCA as you mentioned. It gives an error like this:
    /home/srimantacu/ORCA/orca_2_9_1_linux_i686/orca_gtoint_mpi: error while loading shared libraries: wrong ELF class: ELFCLASS6.
    I got the massage again and again.

    Do you have any idea what would be cause the problem and what to do correct?
    Kindly help me how do I solve this problem.

    Thank you.

  6. benja says:

    From ORCA manual: You did not launch orca with the full path! This is necessary in parallel mode so that ORCA will correctly find its executables… Cheers

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