Large residual errors with AIMD data

[RicardoCecconello]

Dear Dr. Tadano,

I'm doing some calculations of the IFCs with 290 snapshots from AIMD with LMODEL = enet and LMODEL = adaptive-lasso and the residual errors are huge (above 50 %). One issue that I observed is that almost every time I get the error Please use a smaller CV_MINALPHA. I've reduced it to 1.0e-16 and used CV_NALPHA = 100, but I still get the error in some of the CV sets. This occurs mostly when LMODEL = enet, where I have also verified that changing the L1_RATIO value doesn't solve the problem. It happens for different CV values as well. Any ideas on the cause of this problem?

I also checked how the displacement of the atoms (compared to the equilibrium structure) changes on the AIMD trajectory, and I observed that one of the components has a mean displacement 4 times greater than the other ones. Could this be a cause of the problem I'm facing?

Thanks in advance,
Ricardo.

[ttadano]

The large fitting error you observed might be result from the large displacement you mentioned and/or low flexibility of the model.

Can you check if the fitting error is still large with LMODEL = ols?

If the error is still as large as 50% and you need to reduce it further, you will have to make the model more flexible by increasing NORDER or using larger cutoff radii.

[RicardoCecconello]

With LMODEL = ols the error is similar. We'll try with higher NORDER and cutoff. Thank you!