Nexus: Using qdens with updated estimators in batched code

[kayahans]

Describe the bug qdens is not able to produce densities with the updated definition of estimators for the batched code.

To Reproduce Steps to reproduce the behavior: I think this is reproducable on any DMC or VMC batched input file you have available, but in case it fails, please let me know, I will provide the files to reproduce this error.

1. Add "estimators" block in "qmcsystem" block as below:

   <qmcsystem>
   ...
   <estimators>
   <estimator type="spindensity" name="SpinDensity">
   <parameter name="dr">
    0.3 0.3 0.3
   </parameter>
   </estimator>
   </estimators>
   </qmcsystem>

2. Instead of doing this by hand, one can use Nexus: Using the attached nexus file (modified from /nexus/examples/rsqmc_misc/diamond_radial_density/diamond_spin.py), change driver between batched and legacy to observe how the input changes. With legacy option, the correct input file is produced (spindensity inside qmc blocks) , but with batched option, the estimators block is created inside the qmcsystem block (outside hamiltonian block) as above.

Depending on when Nexus is installed, the produced input file is also different. Using Nexus pre Dec 8, 2023 the input file is written using this block of code:

   if batched and d_estimators is not None and len(d_estimators)>0:
         estimators = generate_estimators_batched(d_estimators)
         for calc in kw.calculations:
             if isinstance(calc,loop):
                 calc = calc.qmc
             #end if
             calc.estimators = estimators.copy()
         #end for
     #end if

Using the block of code above, nexus produces the input file with estimators block is created inside qmc blocks (thanks to kw.calculations loop).

In the latest version of Nexus, the loop over kw.calculations is removed and the estimator is added to qmcsystem based on the updated <estimator/> block definition:

    if batched and d_estimators is not None and len(d_estimators)>0:
        ests = generate_estimators_batched(d_estimators,wf_elem=wfn)
        ests_elem = estimators()
        ests_elem.estimators = ests
        sim.qmcsystem.estimators = ests_elem
    #end if

3. With estimator block defined as in (1), qdens complains that there is no density in h5 files, because qdens looks for the spindensity information from the in.xml files and can't find spindensity in hamiltonian or qmc blocks. Using the code below interactively one can load one of the h5 files:

   import h5py
   import numpy as np
   f = h5py.File("dmc.g000.s002.stat.h5", "r")
   ud=f['SpinDensity']['u']['value']
   np.sum(ud[0])
   >>> 104.00075659850167
   ud.shape
   >>> (1000, 235200)

   This file has the correct grid density (dr=0.3, thus 40,40,147), and non-zero.

Expected behavior Qdens should be able to work with the updated definition of <estimator/> element.

System:

• Polaris

Additional context Add any other context about the problem here. diamond_spin.py.zip

[kayahans]

I think I was using an older version of modified qdens in the PATH. New qdens is working as expected.