Support solid-solid transitions in element standard-state formation integrals - #186
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Support solid-solid transitions in element standard-state formation integrals#186gaoflow wants to merge 1 commit into
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The generic standard_state_transitions path in element_standard_state_integral integrated the solid Cp in one piece and ignored solid_T_trans/solid_H_trans, so no element with solid-solid transitions could be expressed. The path now segments the solid integral at each transition temperature and adds the transition enthalpy/entropy when crossed. Activates the commented-out Mn, Ti, Be, and S data (all NIST-JANAF exact); S fixes standard_state_ideal_gas_formation for H2S, SO2, SO3, H2SO4, CS2, and Ti fixes TiO2. Ca and Fe stay commented: Ca's solid Cp fit is ~50% off JANAF, and Fe's Tm value is actually its boiling point. Tests cross-check formation values against the JANAF compound tables and the element paths against JANAF S-001/Mn-001/Ti-001/Be-001.
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standard_state_ideal_gas_formationraisesNotImplementedErrorfor any element outside the20-entry whitelist in
chemical_utils.py. H2S, SO2, SO3, H2SO4, CS2, and TiO2 all crash on ittoday. The whitelist sits right next to six data entries commented out with
# TODO(Mn, Ti,Ca, S, Be, Fe), and an abandoned
elif ele == "S": raise NotImplementedErrorbranch shows thetransition handling was scaffolded and never finished.
Root cause:
element_standard_state_integralintegrates the solid heat capacity in one pieceand ignores the
solid_T_trans/solid_H_transkeys, so no element with solid-solidtransitions could be expressed. The generic path now segments the solid integral at each
transition temperature, adding H_trans to dH and H_trans/T_trans to dS when crossed — the same
formula already used for melt and vaporization. Elements without transitions are unchanged.
Activated Mn, Ti, Be, and S; their commented values are exactly the NIST-JANAF element tables
(S: 368.3 K / 401 J; Mn: 980/1361/1412 K; Ti: 1166 K; Be: 1527 K). Formation values now match
the JANAF compound tables: H2S/SO2/SO3/H2SO4/CS2 and TiO2 within ~1% (tests added, element
paths cross-checked against JANAF S-001/Mn-001/Ti-001/Be-001).
Ca and Fe stay commented: Ca's solid Cp fit in this repo is ~50% off JANAF (the transition
data is right but the integral would be wrong), and Fe's entry has no boiling point — its
Tm: 3133.345is actually the boiling point.Sulfur's 432 K liquid-liquid lambda anomaly (noted in the old branch's comment) is not modeled;
the commented data omits it.
Repro before:
standard_state_ideal_gas_formation(Chemical('H2S'), 400.0)→ NotImplementedError.After: computes, matches JANAF H-080 at 1% rtol.
pytest tests/test_chemical_utils.py32 passed.