Simple Coverage Workflow

The simple coverage workflow obtains a stable, simple coverage estimate. It does so by iteratively relaxing the coverage structure by DFT and removing too close adsorbates. So far, only atomic adsorbates are supported.

Given a nanocluster structure, the adsorption sites are mapped out as described in the Singlesites Workflow tutorial. Similarly adsorbate_name defines which atomic adsorbate is placed onto sites classified as “top”, “bridge” and/or “hollow” in adsite_types.

Since the cluster is would likely be overpopulated, the amount of adsorbates is pre-reduced: either the user defines the target number of remaining adsorbates (n_remaining) or a inter-adsorbate minimum distance (bond_length). If n_remaining is given, bond_length is ignored in this step.

After each DFT relaxation, it is checked if any two adsorbate atoms have formed a molecule. Too close adsorbates (specified by bond_length) are consequently removed.

If no adsorbates are too close, the search has converged and the workflow stops. Otherwise, it continues for max_iterations.

At one glance, these are the simple-coverage-workflow-specific parameters:

adsorbate_name (str)

element symbol of the adsorbed atom

max_iterations (int)

maximum number of iterations in the workflow

adsite_types (list)

adsorption site types, can contain any combination of “top”, “bridge”, “hollow”

bond_length (float)

distance in angstrom under which two adsorbed atoms are considered bound, hence too close

n_remaining (int)

number of adsorbates which should remain after the first pre-DFT pruning of the adsorbate coverage