Units of energy gradients of standalone MBX

[Jelto Neirynck (Ratapup)]

Dear MBX developers

I want to create an MLP that is partially trained on the energies and forces calculated by MBPOL (using Δ-learning) as my system contains a lot of water. For this, I want to use the standalone MBX package installed on the HPC I use as a reference calculator. The problem I'm having is that I am not sure what the units of the Energy gradients are, as I cannot find them in the documentation. Since the energy is given in kcal/mol, I assume that the gradients are given in kcal/mol/Å but I need to be 100% sure before I waste computational resources on the wrong units. Are they given in kcal/mol/Å,  kcal/mol/Bohr or directly in atomic units?  I use the Python code to calculate the energies and gradients as in the examples of GitHub.

I thank you in advance for your help and time.

Kind regards

Jelto Neirynck

[Philip Zhu]

Hi Jelto, kcal/mol/Å is correct.