Download and Install Latest Q-Chem

Before you begin

A valid order number is required to proceed with installation. If you do not have an order number, please register for a demo license. If you have registered before and lost your order number, contact our support team at support@q-chem.com.

Choose your operating system

Q-Chem can be installed on Linux, macOS or Windows running on x86 64-bit systems (Intel, AMD). The shared-memory version of Q-Chem is recommended for most laptops, workstations and computer clusters. Some Q-Chem features are available with across-node MPI parallelism on clusters and supercomputers.

Linux installation instructions

1. Download the installer

   wget -N https://downloads.q-chem.com/qcinstall.sh

2. Set executable permissions on the downloaded installation script

   chmod +x qcinstall.sh

3. Launch the installer script

   ./qcinstall.sh

4. Follow through the steps of the Q-Chem installation guide

macOS installation instructions

1. Download the installer

   curl https://downloads.q-chem.com/qcinstall.sh > qcinstall.sh

2. Set executable permissions on the downloaded installation script

   chmod +x qcinstall.sh

3. Launch the installer script

   ./qcinstall.sh

4. Follow through the steps of the Q-Chem installation guide

Windows installation instructions

For instructions on setting up IQmol using a local server with Windows, please click here.

1. Download the Q-Chem 6.2 installer for Windows or Q-Chem 6.1+BrianQC installer for Windows.

2. Launch the installer and follow its prompts. (For those downloading the installer soon after the release, there may be a "Windows Protected Your PC" warning when you first try to launch it; select "More info" and then click the "Run anyway" button to proceed. Only do this if you downloaded the executable via the link above.)

3. The default installation directory is C:\Q-Chem\6.2.0.

4. For Windows 10 or earlier, under "Start Menu\Q-Chem 6.2.0", click "Register Q-Chem" and follow registration prompts. For Windows 11, navigate to the Start Menu and select All Apps, select "Q-Chem 6.2.0", click "Register Q-Chem" and follow registration prompts.

5. Save the license file received from us by email as C:\Q-Chem\6.2.0\qcaux\license\qchem.license.dat

6. After the license is received and installed, please verify the installation by running a sample calculation. Start "Q-Chem Shell" in "Start Menu\Q-Chem 6.2.0" (or "Start Menu\All Apps\Q-Chem 6.2.0" in Windows 11), and type the following command to verify.

   qchem dft_b3lyp_h2o.in

Offline installation and previous Q-Chem releases

Current and previous versions of Q-Chem for Linux and macOS are available as downloadable installation tarballs. These are useful when the target computer does not have Internet access, the normal installation process fails, or an older version of Q-Chem is desired. Please note that only current version of Q-Chem is supported, and we may not be able to resolve technical issues with previous Q-Chem releases.