I am currently looking into the parameters of 2NN-MEAM potentials available at openKIM using Kliff. As an example I use the commands
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from kliff.models import KIMModel
model = KIMModel(model_name=“MEAM_LAMMPS_LeeLee_2014_ZrH__MO_946208788356_002”)
model.echo_model_params()
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When I list the parameters as indicated above, it seems that some of the potential parameters are missing. I am thinking primarily of the t0, t1, t2 and t3 and beta0, beta1, beta2 and beta3 parameters, which I cannot identify in the printed list. I am not sure if there are other parameters missing from the list too.
My questions are: Is there anyway to extract the missing parameters? And, if I wish to use Kliff to refit the parameters that are not printed in the list, how should I go about?
you’re correct that the t0, t1, t2, t3, beta0, beta1, beta2, and beta3 parameters are standard MEAM parameters that are currently non-mutable and not exposed for change. The echo_model_params() function only reports the mutable parameters. If you need to refit these parameters, please let me know and I’ll be happy to discuss the possibility of making them mutable in a future release. I’m planning to release a new version of the model soon with additional MEAM versions, so it’s a good time to consider this.
Thank you for the quick response and clarification!
For me personally, I think that it would be beneficial if most parameters describing the potential were made mutable. This would offer more flexibility when fitting, and if you want to keep them fixed to the default/original values - from my understanding - I believe that you could specify that in kliff. I suspect that it would be especially useful whenever you are trying to refit potential to a different database than that used for the original potential, or if you want to fit a potential from scratch.