Special Opacities#

Special opacities are continuum sources that are not handled by the line, CIA, or Rayleigh registries. In the current codebase this is the H⁻ (H-minus) continuum, split into:

bound-free: exo_skryer.opacity_special.compute_hminus_bf_opacity()
free-free: exo_skryer.opacity_special.compute_hminus_ff_opacity()

The forward model uses exo_skryer.opacity_special.compute_special_opacity() to sum all enabled special-opacity contributions.

Enabling H⁻ in YAML#

Two separate switches are involved:

Enable special opacity in the forward model (kernel runs):

physics:
  opac_special: ck   # or os, or on

Enable which H⁻ tables are built/loaded (registry contents):

opac:
  special:
    - {species: H-, bf: true, ff: true}

Requirements#

H⁻ bound-free (bf)

Requires the VMR key "H-" in state["vmr_lay"]. In constant-VMR chemistry this typically means including H- as a retrieved trace species (e.g. log_10_f_H- / clr_H- depending on chemistry mode).

H⁻ free-free (ff)

Requires:

atomic hydrogen VMR key "H" in state["vmr_lay"] (for constant-VMR modes, add parameter log_10_H_over_H2 so H can be derived from the H2+He filler)
parameter log_10_ne_over_ntot in the retrieval parameter list (proxy for electron fraction).