Data supporting the calculations in the paper. These include the input and output files for the Quantics program to run DD-vMCG and iMCG simulations of a GFP cluster model, as well as the database files with the quantum chemistry results. These files can be used together with Quantics to generate the data in the paper Bourne-Worster and Worth (JCP, 160, 065102, 2024). The input files are standard ascii files, grouped into directories for the different systems studied. The databases with the points calculated during the direct dynamics simulations are SQLite format with tables for geometries, energies, gradients etc. More details are in the paper. The Quantics program is a mostly Fortran code for running quantum dynamics simulations. It is open source and runs on linux workstations. It is freely available on request to the authors of the paper. For further details of the program see Comp. Phys. Comm., 248:107040–15, 2020.