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atomref.xh

This module provides the provisional X–H bond-length helpers available in the current release line.

It is intentionally narrow:

  • one packaged sparse target dataset, csd_legacy_xh_cno,
  • one wrapper policy, XHPolicy,
  • convenience helpers for listing packaged X–H sets and resolving X–H values.

The built-in quantity is keyed by the parent element X in X–H and is currently aimed at hydrogen-position normalisation or related geometry workflows.

In the default policy:

  • C, N, and O use curated ConQuest/CSD defaults,
  • other parent elements may be inferred from cordero2008,
  • policy-backed predictors are supported as well, with conservative nested-fit defaults and one additional nested prediction step allowed by default,
  • fuller X–H literature support is planned for 0.2.x.

atomref.xh

X-H bond-length helpers built on the generic policy core.

DEFAULT_XH_POLICY = XHPolicy(base_set='csd_legacy_xh_cno', transfers=(LinearTransfer(predictors=(DatasetRef('covalent_radius', 'cordero2008'),), min_points=3, exclude_placeholders=True),)) module-attribute

Default X-H policy used by the convenience helpers.

XHPolicy dataclass

Policy wrapper specialized for parent-element X-H bond lengths.

The quantity key is fixed to "xh_bond_length" and uses the parent element X as the lookup key. H itself is not considered a valid parent element for this quantity.

as_value_policy()

Convert the X-H policy into the generic scalar-value policy.

get_xh_bond_length(symbol, *, policy=None)

Return only the selected X-H bond-length value, without provenance.

get_xh_set(set_id)

Load one packaged X-H set as an :class:ElementScalarSet.

get_xh_set_info(set_id)

Return metadata for one packaged X-H set.

list_xh_set_infos(*, usage_role=None)

Return packaged metadata objects for X-H sets.

list_xh_sets(*, usage_role=None)

List packaged X-H set ids.

lookup_xh_bond_length(symbol, *, policy=None)

Resolve a parent-element X-H bond length with provenance.