Fitsvsl: Did not find spring in make_nn_forcek. Ignoring

It’s a spinel system A(B1,B2)O3. Such a problem didn’t happen to other systems before and I’ve done quite a few calculations.

The first step creating displacements worked with

fitsvsl -er 10 -ns 2 -ms 0.02

But when I do

fitsvsl -f

After reading displacements outputs like "73) Reading 7/vol_2/p+0.2_10_7", many lines of "Did not find spring in make_nn_forcek. Ignoring" showed up.

Perhaps try changing the -z=… value?
Sending a tar file of your attempt would be useful (without large vasp files).