easy to start a FEP
After getting feprepare.zip from https://feprepare.vi-seem.eu/indexlpg.php and NAMD_3.0alpha8_Linux-x86_64-multicore-CUDA/namd3 from https://www.ks.uiuc.edu/Research/namd/, running scripts from 1 to 5, and analysising with your local VMD.
https://www.ks.uiuc.edu/Research/namd/