Fail to load Ensemble saved by sscha.Relax.SSCHA(save_ensemble = True)

[jav-montoya]

After setting "save_ensemble = True" in sscha.Relax.SSCHA and running a few iterations before a CRASH, I am not able to restart because "relax.vc_relax(restart_from_ens = True)" doesn't load the population from my "relax.data_dir", even after I point to it with "ensemble_loc" inside relax.vc_relax.

Also, the ensemble data stored in my "relax.data_dir" is not compatible with the "load" or "load_bin" functions for the ensemble object, nor mine is a remote calculation that stores what is needed for using the function "load_from_calculator_output". The final population content saved in my "relax.data_dir" location before the crash is:

"dyn_gen_pop7_1 dyn_gen_pop7_4 dyn_gen_pop7_7 xats_pop7.npy all_properties_pop7.json
dyn_gen_pop7_2 dyn_gen_pop7_5 dyn_gen_pop7_8 forces_pop7.npy
dyn_gen_pop7_3 dyn_gen_pop7_6 energies_pop7.npy stresses_pop7.npy"

How do I go about reloading this ensemble and restarting my "relax.vc_relax(restart_from_ens = True)" ?

[mesonepigreco]

Hi,
The restart works by manually loading a precomputed ensemble:

# Load the ensemble
ensemble = sscha.Ensemble.Ensemble(dyn_start, temperature)
ensemble.load_bin("data_dir", 7)  
# Load bin works by taking the directory on which the ensemble is saved and the population id
# This coincides with the data_dir of relax directory, and, in your case, the 7th population

# Initialize the minimizer
minim = sscha.SchaMinimizer.SSCHA_Minimizer(ensemble)

# Initialize the relax
relax = sscha.Relax.SSCHA(....)

# [ ... ]
relax.vc_relax(restart_from_ensemble=True)

In this way, the first iteration of the vc_relax will be performed without regenerating the ensemble.
If, instead, the calculation crashed during the ensemble generation, and it has not correctly saved, if you have the output file of the calculator (like espresso .pwo), you can use the load_from_calculator_output, passing the directory containing all the output files. The code will automatically parse the structures and rebuild the ensemble. Note that in this case it is important that the dynamical matrix used to initialize the ensemble (dyn_start in the snippet above) is the same as the one that generated the configurations.

[jav-montoya]

Thank you for your kind and prompt answer, I followed the instructions and my python script now works very close to what is expected. Since "ensemble.load_bin" is the function that works fine in this scenario, I suggest to clarify somewhere in the documentation that by setting "save_ensemble = True" in the sscha.Relax.SSCHA object, the code is implicitly using the "save_bin" function of the ensemble module.

I would appreciate learning what is the usage scenario of the "ensemble_loc" parameter in the relax module, since I was under the impression that this, together with "restart_from_ensemble=True", would suffice to achieve the same result that one gets with the manual loading process that you explained here.