Both G-FMPES and HCFF suffer from two drawbacks: Firstly, the user can only guess the simulated pressure when setting up a calculation. Secondly, atoms are always pushed to the center of mass of the molecule, leading to unphysical, sphere-like geometries for extended systems, such as alkanes, if high pressure is applied. The eXtended Hydrostatic Compression Force Field (X-HCFF) approach solves these drawbacks by defining forces f ij acting perpendicular to the discretized Van-der-Waals surface of a molecule from each discretization point i to the closest atom j. The force is scaled using the classical definition of pressure as