The RBFE calculations performed in this work are calculated using three molecular dynamics packages; these are NAMD2, NAMD3 and OpenMM. OpenMM can perform MD calculations on multiple platforms (CPU, CUDA, OpenCL); in this work all OpenMM calculations are performed using the CUDA platform with OpenMM 7.4.2. The NAMD2 calculations are performed on CPUs and NAMD 3.08 alpha calculations are performed on GPUs.