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Hi everyone,

I just encountered an error problem "Error: RATTLE_vel algorithm did not converge!" when I tried to run NpT for a relatively large box (50 \AA^3), with constraints on the lattice angles in ICONST. It seems to be a general problem for large systems and that LANGEVIN_GAMMA, LANGEVIN_GAMMA_L and PMASS are relevant, but I have no idea about in which way I should vary them to solve the problem. These paramters in my INCAR are set to be:
LANGEVIN_GAMMA = 10 10 10
LANGEVIN_GAMMA_L = 10
PMASS = 1000
I did have tried to vary some of them, but the problem remains. Any clue on that?

Thank you very much and happy 2025!

Hi Renjie,

Thank you for your question. Could you attached the POSCAR, POTCAR, KPOINTS, INCAR, and OUTCAR and we can take a look at it. Do you encounter the same problems in a smaller system? Generally it is best to find the best parameters for a cheaper system before scaling to a larger one.

Happy new year!

Best wishes,

Chris