32-bit G16M and macOS Catalina

This information applies only to the 32-bit version of Gaussian 16 for macOS, referred to as G16M below, which is licensed only for individual computers.
All 64-bit versions of Gaussian 16 for macOS will work fine with macOS Catalina.
All site licenses covering/including the macOS version of Gaussian 16 are the 64-bit version.

The single seat version of G16M is a 32-bit application. macOS Catalina removes support for 32-bit applications. Accordingly, G16M users should not upgrade to macOS Catalina if they plan to continue running the program. The same consideration will apply to 32-bit versions of G09M and GV5M and earlier software versions.

Determining whether Gaussian 16 is 32-bit or 64-bit

Performing this task requires using the Terminal application.

The following command will work in most cases:

$ file $g16root/g16/l1.exe
/3/g16/l1.exe: Mach-O 64-bit executable x86_64

The 64-bit version is installed on this computer.

If the previous command gets an error like g16root: undefined variable, then the following command will work if the Gaussian 16 executables are in the search path:

file `which l1.exe`

If the previous command fails with errors, but you know the location of the Gaussian 16 installation directory, you can supply it explicitly to the file command:

file /full/path/to/g16/l1.exe

If you don’t know where Gaussian 16 is installed, the following long-running command will locate and examine it provided that you have access to it:

find / -name l1.exe -type f -exec file {} \; 2>&1 | grep l1

Last updated: 15 October 2019