Add nbands_factor logic into PdosWorkChain (#1044)

Introduce a new input parameter, `nbands_factor`, to the PdosWorkChain. This parameter replicates the functionality available in the BandsWorkChain, allowing the calculation of additional bands during the PwCalculation (NSCF). It ensures that an appropriate number of extra bands are computed. This enhancement provides more flexibility and consistency in the band structure and PDOS workflows.

src/aiida_quantumespresso/workflows/pdos.py

@@ -118,6 +118,9 @@ def validate_inputs(value, _):
             if value['dos']['parameters']['DOS'].get(par, None) is None:
                 return f'The `{par}`` parameter must be set in case `align_to_fermi` is set to `True`.'
 
+    if 'nbands_factor' in value and 'nbnd' in value['nscf']['pw']['parameters'].base.attributes.get('SYSTEM', {}):
+        return PdosWorkChain.exit_codes.ERROR_INVALID_INPUT_NUMBER_OF_BANDS.message
+
 
 def validate_scf(value, _):
     """Validate the scf parameters."""
@@ -227,6 +230,9 @@ def define(cls, spec):
                 'provided by in the `dos` and `projwfc` inputs, since otherwise the '
             )
         )
+        spec.input('nbands_factor', valid_type=orm.Float, required=False,
+            help='The number of bands for the NSCF calculation is that used for the SCF multiplied by this factor.')
+
         spec.expose_inputs(
             PwBaseWorkChain,
             namespace='scf',
@@ -301,6 +307,8 @@ def define(cls, spec):
             message='the PROJWFC sub process failed')
         spec.exit_code(404, 'ERROR_SUB_PROCESS_FAILED_BOTH',
             message='both the DOS and PROJWFC sub process failed')
+        spec.exit_code(405, 'ERROR_INVALID_INPUT_NUMBER_OF_BANDS',
+            message='Cannot specify both `nbands_factor` and `nscf.pw.parameters.SYSTEM.nbnd`.')
 
         spec.expose_outputs(PwBaseWorkChain, namespace='nscf')
         spec.expose_outputs(DosCalculation, namespace='dos')
@@ -426,11 +434,23 @@ def run_nscf(self):
 
         """
         inputs = AttributeDict(self.exposed_inputs(PwBaseWorkChain, 'nscf'))
+
         if 'scf' in self.inputs:
             inputs.pw.parent_folder = self.ctx.scf_parent_folder
+
+        if 'nbands_factor' in self.inputs:
+            inputs.pw.parameters = inputs.pw.parameters.get_dict()
+            factor = self.inputs.nbands_factor.value
+            parameters = self.ctx.workchain_scf.outputs.output_parameters.get_dict()
+            nbands = int(parameters['number_of_bands'])
+            nelectron = int(parameters['number_of_electrons'])
+            nbnd = max(int(0.5 * nelectron * factor), int(0.5 * nelectron) + 4, nbands)
+            inputs.pw.parameters['SYSTEM']['nbnd'] = nbnd
+
         inputs.pw.structure = self.inputs.structure
 
         inputs.metadata.call_link_label = 'nscf'
+
         inputs = prepare_process_inputs(PwBaseWorkChain, inputs)
 
         if self.ctx.dry_run: