[newchem-cpp] transcribe calc_all_tdust_gasgr_1d_g

[ChristopherBignamini]

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[ChristopherBignamini]

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[ChristopherBignamini]

pre-commit.ci autofix

[mabruzzo]

This looks great. There's unfortunately a complication.

The Complication:

I forgot to reiterate that you should be doing the dust chemistry transcription stuff working off of PR #447 (it would probably be even better to work off of #464)

For some context:

1. (most importantly for this PR), PR [newchem-cpp] introduce GrainMetalInjectPathways type #447 did a bunch of work reorganizing a bunch of "loose" constants from the chemistry_data_storage type (commonly known held by the my_rates variable)
2. it also adds a bunch of comments to some of the remaining fortran functions

How to fix this

Important

Let me know if you would prefer that I just pull a copy of this branch and fix the issues myself. It would probably only take ~15 minutes

In any event, I think the best path forward is to merge #464 into this PR, and then stack the remaining transcription PRs off of this one.

When you merge #464 onto this PR, there is going to be a minor merge-conflict. The easiest way to solve this involves:

1. insert "#include "inject_model/grain_metal_inject_pathways.hpp" and #include "opaque_storage.hpp" into the top of calc_all_tdust_gasgr_1d_g.cpp.

2. insert the following block of code into the top of the calc_all_tdust_gasgr_1d function:

  grackle::impl::GrainMetalInjectPathways* inject_pathway_props =
    my_rates->opaque_storage->inject_pathway_props;

  double dlog10Tdust = 0.0;
  double* log10Tdust_vals = nullptr;

  // NOTE: gr_N and gr_Size are historical names
  // -> they are pretty uninformative and should be changed!
  int gr_N[2] = {0, 0};
  int gr_Size = 0;
  if (inject_pathway_props != nullptr) {
    dlog10Tdust =
      inject_pathway_props->log10Tdust_interp_props.parameter_spacing[0];
    log10Tdust_vals =
      inject_pathway_props->log10Tdust_interp_props.parameters[0];

    gr_N[0] = inject_pathway_props->n_opac_poly_coef;
    gr_N[1] = static_cast<int>(
      inject_pathway_props->log10Tdust_interp_props.dimension[0]);
  };
  gr_Size = gr_N[0] * gr_N[1];

3. do the following search and replaces:
   • replace my_rates->gr_N with gr_N
   • replace my_rates->gr_Size with gr_Size
   • replace my_rates->gr_dT with dlog10Tdust
   • replace my_rates->gr_Td with log10Tdust_vals

[mabruzzo]

While you are making the changes, it would be great if you could move the file into the dust sub-directory (but no pressure if you don't get to it)

[mabruzzo]

Just an FYI: when you do the merge make sure you use the most up-to-date version of PR #464. There were some annoying merge conflicts between that branch and the main branch that I resolved yesterday

[ChristopherBignamini]

pre-commit.ci autofix

[mabruzzo]

Looks good to me! I left a few superficial suggested changes to tweak the format of some comments. But, I'm happy to merge now and deal with those later.

Note for when you resolve the merge conflicts:

• if #521 has been merged into newchem-cpp, everything will be great
• if #521 hasn't been merged upstream yet, you should explicitly merge it here before you format the code. (That PR properly fixes a clang-format error, whereas the default automatic fix moves happens to move a // NOLINT comment to a bad location)

@brittonsmith, I'm happy to see this merged

[mabruzzo]

Suggested change

	// -> this is ONLY used when `itmask_metal .eq. MASK_TRUE`
	// -> this is ONLY used when `itmask_metal[i] == MASK_TRUE`

[mabruzzo]

Suggested change

	// ! in UV, absorption coefficient Q ~ 1 (Goldsmith 2001)
	// ! so we use the geometrical cross-section of grains [cgs]
	// in UV, absorption coefficient Q ~ 1 (Goldsmith 2001)
	// so we use the geometrical cross-section of grains [cgs]

[mabruzzo]

Suggested change

	// ! correct with the depletion or enhancement of condensation rate.
	// correct with the depletion or enhancement of condensation rate.

[mabruzzo]

Suggested change

	/// modified: January, 2026 by Christopher Bignamini & Matthew Abruzzo; C++ port
	/// modified: January, 2026 by Christopher Bignamini; C++ port