Input reference (TOML)

Every key the ferric CLI accepts, section by section.

Unknown keys are a hard error. The config structs in crates/ferric-cli/src/config.rs are #[serde(deny_unknown_fields)], so a misspelled key or section aborts the run before anything is computed. That includes [external_potential], its point charges, and each [[scf.ladder]] rung.

String values go through strict parsers, where an unknown value is an error at load time rather than a default. Most accept any capitalisation; the exceptions are noted per key.

This page is hand-maintained against crates/ferric-cli/src/config.rs at commit 4b64e6ce. Where a default is applied at the point of use rather than in config.rs, it was read from crates/ferric-cli/src/lib.rs at the same commit. If the code and this page disagree, the code wins. For which method.kind values exist and what each supports, see Capabilities and validation.

Units follow the code: [molecule] geometries are Å (XYZ), point charges and cutoffs named *_bohr are Bohr, keys named *_angstrom or documented as Å are Å, and energies are Hartree.

A minimal file:

[molecule]
xyz = "testdata/molecules/water.xyz"
[basis]
name = "cc-pvdz"
[method]
kind = "rimp2"
[mp2]
auxbasis = "cc-pvdz-ri"

`[molecule]` (required)

Key	Type	Default	Allowed values	Notes
`xyz`	string	required	path	Standard XYZ in Å, relative to the working directory. Not read when `[qmmm]` is present (the PQR supplies the geometry).
`charge`	integer	`0`		With `[qmmm]`, applies to the QM region.
`multiplicity`	integer	`1`	≥ 1	Read by `uhf`, `rohf` and `ksdft` (UKS) for every task, and for `task = "energy"` only by `rimp2`/`oo-rimp2` (UHF + unrestricted RI-MP2 / OO-RI-MP2) and the open-shell path of `pdep-rpa`/`gw`/`mp2-v`: UHF, or UKS when `[rpa] xc` is set (`pdep-rpa`, `gw`), or ROHF/ROKS for `gw` with `[gw] reference = "rohf"`; `mp2-v` stays UHF. Every other kind refuses `> 1`. See open shells.

`[basis]` (required)

Key	Type	Default	Allowed values	Notes
`name`	string	—	a bundled name (case-insensitive)	`sto-3g`, `6-31g`, `cc-pvdz`, `cc-pvtz`, `aug-cc-pvdz`, `aug-cc-pvtz`, `aug-cc-pvqz`, `aug-cc-pvdz-pp`, `aug-cc-pvtz-pp`, `def2-svp`, `def2-tzvp`, `def2-qzvp`, `cc-pvdz-f12`.
`path`	string	—	path to a Gaussian-94 file	Used only if `name` is absent. One of `name`/`path` is required.

Auxiliary basis names used elsewhere (auxbasis, df_*_aux) come from the same table: cc-pvdz-ri, cc-pvtz-rifit, aug-cc-pv{d,t,q}z-rifit, def2-svp-rifit, def2-tzvp-rifit, def2-tzvpp-rifit, def2-qzvp-rifit, def2-qzvpp-rifit, def2-universal-jkfit, cc-pvdz-f12-optri. cc-pvdz-rifit is an alias of cc-pvdz-ri; both names load the same set.

`[method]` (required)

Key	Type	Default	Allowed values	Notes
`kind`	string	required	`rhf` `uhf` `rohf` `ksdft` `rimp2` `mp3` `oo-rimp2` `att-rimp2` `mp2-v` `scs-mp2` `scs-mp2-2terfc` `laplace-mp2` `laplace-sos-mp2` `pdep-rpa` `rs-mp2-rpa` `gw` `bse-tda` `tdhf-static-polarizability` `ccsd` `ccd` `ccsd(t)` `linlccd` `drpa` `wb97x-l-v` `b2plyp` `dsd-pbep86` `tda` `tddft`	Any other value is an error. Smoke- and Spike-grade kinds print a `[warning]` grade line on stderr; Proven kinds and the ungraded `laplace-sos-mp2` print none. `rimp2`, `drpa` and `linlccd` name the method and are computed exactly unless `[local]` sets a local approximation (see Capabilities and validation).
`task`	string	`"energy"`	`energy` `optimize` `frequencies`	`optimize`: `rhf` `ksdft` `uhf` `rohf` `rimp2` `pdep-rpa` only. `frequencies`: `rhf` `ksdft` `uhf` `rohf` only.

`[scf]`

Read by every kind, because every kind runs an SCF first.

Key	Type	Default	Allowed values	Notes
`max_iter`	integer	`100`
`energy_conv`	float	`1e-3`		Sanity bound, not a target. Convergence requires `ΔP_rms < density_conv`, `ΔP_max < 10·density_conv` and `ΔE < energy_conv`. `ΔE` floors on the RI noise, so tightening this can make a density-fitted run hit `max_iter`.
`density_conv`	float	`1e-6`		The real convergence signal.
`diis_size`	integer	`8`
`diis`	string	`"pulay"`	`pulay` `adiis` `ediis` (case-insensitive)	An unknown value is an error when the file is loaded.
`diis_switch_thresh`	float	`1e-1`		Error level at which ADIIS/EDIIS hand over to Pulay. Ignored for `pulay`.
`smearing_sigma`	float	none	Hartree	Fermi–Dirac smearing width. Absent means integer occupations.
`guess`	string	`"minao"`	`minao` `sad` `hcore` (case-insensitive)	`"sad"` is an alias of `"minao"` (the MINAO projection guess); the free-atom-SCF SAD guess is not selectable from config. Any other value is an error.
`soscf`	bool	`false`		Enables the second-order (Newton) step in the SCF tail.
`integral_thresh`	float	`1e-12`		Integral screening threshold.
`eri_precision`	float	`1e-20`	`0` to `1e-8`	libint primitive-screening precision for the SCF J/K integrals. Omitted: `FERRIC_ERI_PRECISION` if set, else `1e-20`. `1e-14` costs up to 6e-9 Ha in E_J for atoms past Ne; `0` disables primitive screening (1.8–5.7× slower per J/K build).
`screening`	string	`"schwarz"`	`schwarz` `csb` `csam`	`csb` is rigorous and never looser than `schwarz`. `csam` is not a bound. It is refused for erfc (short-range) operators. See SCF: screening.
`k_builder`	string	`"direct"`	`direct` `link` `cosx`	Exchange builder. `cosx` with RI-J active (named, or the Kohn-Sham default) is RIJCOSX: J from RI-J, K from COSX, and the RI-K default is not applied; `cosx` next to an explicitly named `df_k_aux` is an error. `link` is ignored with a warning when DF-J/DF-K is active. Both are ignored with a warning for functionals with no exact exchange and for range-separated functionals. See SCF: choosing how exchange is built.
`cosx_grid`	inline table	`{ radial = 35, angular = 194, prune = "sgx" }`	`angular` ∈ 6/14/26/50/110/194/302/434/590; `prune` ∈ `none` `sgx` `nwchem`	The COSX SCF grid. A table without `prune` is flat; with `prune = "sgx"`, `angular` is the peak order of the pruned rows (50/110/194/302/434/590). Only with `k_builder = "cosx"`; otherwise it is an error. The inner table is strict.
`cosx_final_pass`	bool	`true`		Re-evaluate exchange once on a larger grid at the converged density and report that energy (the SCF-grid energy is printed and logged too). Without `cosx_final_grid` the grid is `{ radial = 50, angular = 302, prune = "sgx" }`. Gradient tasks run without it; ROHF/ROKS skips it with a note (an explicit `true` there is an error). Only with `cosx`.
`cosx_final_grid`	inline table	none	as `cosx_grid`	The final-pass grid; setting it turns the pass on (`cosx_final_pass = false` with it is an error). RHF/RKS and UHF/UKS only. Only with `cosx`.
`cosx_overlap_fit`	bool	`true`		Only with `cosx`; otherwise it is an error.
`cosx_backend`	string	`"md3c1e"`	`md3c1e` `cosx-a`	Only with `cosx`; otherwise it is an error. `cosx-a` is the slower cross-check kernel.
`cosx_screen_thresh`	float	`1e-7`	≥ 0	Only with `cosx` and `md3c1e`. `0` disables the screen.
`cosx_half_transform`	string	`"sparse"`	`sparse` `dense`	Only with `cosx`.
`df_j_aux`	string	none; `def2-universal-jkfit` for `ksdft`, `pdep-rpa`, `rs-mp2-rpa`, `gw`, `bse-tda`, `tdhf-static-polarizability`, `tda`, `tddft`	aux basis name, or `""`	RI-J. With neither key set, `rhf`/`uhf`/`rohf` use exact 4-index J/K. `df_j_aux = ""` selects exact J for the kinds that default to RI-J (the `SCF J/K` log line then reads `RI-JK via` with a blank name). Unlike Python's `run_dft`, the CLI does not accept `"exact"`, `"none"` or `"off"`: any non-empty value is looked up as a basis name, and an unknown one fails the SCF.
`df_k_aux`	string	as `df_j_aux`	aux basis name, or `""`	RI-K. Use a JK-fit set. `""` selects exact K.
`level_shift`	float	`0.0`	Hartree	Virtual-block shift. Left at 0 with a meta-GGA functional, the library applies 0.5.
`mom_after_iter`	integer	`0`		Maximum-overlap occupation pinning after this many iterations. `0` = aufbau throughout.
`verbose`	bool	`false`		One line per SCF iteration. The CLI's `--verbose`/`-v` flag ORs into this.
`df_guess`	bool	on		Two-stage SCF: DF first, then exact. It applies only on the closed-shell, non-laddered path (`rimp2` and the other correlated kinds). `rhf`/`ksdft` use the convergence ladder, which does not compose with it, and `lib.rs` prints a warning there whenever it is enabled, including by default. Mutually exclusive with an explicit `df_increments = true`.
`df_guess_aux`	string	`def2-universal-jkfit`	aux basis name	It is an error when `df_guess` is off.
`df_increments`	bool	`false`		DF-corrected incremental Fock SCF. Same scope as `df_guess`, and warned and ignored on `rhf`/`ksdft`.
`df_increments_aux`	string	`def2-universal-jkfit`	aux basis name	It is an error when `df_increments` is off.
`check_stability`	bool	`false`		Diagnostic only: warns if the solution is a saddle point and never fails the run. On an RHF/HF run it reports TWO verdicts — internal (the singlet channel, is this RHF solution an RHF minimum?) and external RHF→UHF (the triplet channel, does breaking spin symmetry lower the energy?) — because a stretched geometry is routinely internally stable and externally a saddle: water / 6-31G at r(OH) = 2.0 Å gives +1.97e-2 and −3.07e-1. An external instability's remedy is to run `kind = "uhf"`, not to re-converge RHF. RKS gets the internal verdict only (no triplet XC kernel, printed as a skip); UHF/UKS get the internal verdict, which already spans the independent α/β rotations. ROHF/ROKS, range-separated and meta-GGA are skipped entirely with a printed reason.
`stability_descent`	bool	`false`		State selection: at a saddle of the orbital Hessian (UHF, or the RHF singlet channel), follow the downhill eigenvector and re-converge, keeping the lowest state. Turns `check_stability` on as well. Same as Python `run_uhf(stability_descent=True)`. Only `kind = "rhf"`, `"uhf"` or `"ksdft"` with `task = "energy"`; any other kind or task is an error. A KS functional with no stability verdict (range-separated, meta-GGA) skips the descent with a printed reason. Costs one Davidson per converged solve plus one SCF per descent. See `examples/o2-uhf-stability-descent.toml`.
`ladder`	array of tables	built-in ladder	see below	`[[scf.ladder]]` rungs. Read only by `rhf` and `ksdft`.

`[[scf.ladder]]` rungs

Each rung overrides the flat [scf] settings. The rungs are walked in order, and the ladder stops at the first converged rung. Unknown keys are an error, as elsewhere.

Key	Type	Default	Allowed values	Notes
`guess`	string	`"minao"`	`minao` `sad` `hcore`	As `[scf] guess`: `"sad"` is an alias of `"minao"`, and any other value (including `sad-smallbasis`) is an error.
`level_shift`	float	inherits
`max_iter`	integer	inherits
`df_j_aux`, `df_k_aux`	string	inherits
`stall_window`	integer	none
`divergence_tol`	float	none
`restart`	bool	`false`		`true` discards the incoming density.

`[dft]`

Key	Type	Default	Allowed values	Notes
`functional`	string	`"LDA"` (for `ksdft`)	an XC name (`LDA`, `PBE`, `B3LYP`, `wB97X-V`, `SCAN`, `r2SCAN`, …) or a libxc name	Read by `ksdft`. `wb97x-l-v` ignores it with a warning. RPA/GW use `[rpa] xc` and TDDFT uses `[tddft] xc` instead.
`grid_prune`	string	`"none"`	`none` `off` `flat`; `nwchem` `nwchem-like` `nwchem_like`	Prunes the main grid only. Accepted only with `task = "energy"`.
`grid_radial`	integer	`75`	> 0	Radial points per atom on the main grid. Only on a run with a Kohn–Sham grid, only with `task = "energy"` (the XC gradient uses the default grid), and not with `kind = "gw"`. Same as Python `grid_radial=`.
`grid_angular`	integer	`110`	`6` `14` `26` `50` `110` `302` `434` `590`	Lebedev order on the main grid. Same scope as `grid_radial`. An unsupported order is an error. Same as Python `grid_angular=`.
`dispersion`	string	absent	`d3bj`, `d3(bj)`, `d3bj(<functional>)`, `mbd`, `mbd(<functional>)` (case-insensitive)	Only on a Kohn–Sham SCF (`kind = "ksdft"`, or `rhf`/`uhf`/`rohf` with `functional`). `task = "optimize"` runs on RKS, UKS and ROKS references; `task = "frequencies"` is closed-shell only and uses finite differences of the KS + dispersion gradient, so `[frequencies] hessian = "analytic"` is an error. There is no "off" value; omit the key instead. A functional with no published D3(BJ) fit or MBD@rsSCS β (PBE, PBE0, HSE06) is an error.
`lambda`	float	`0.6`		Only for `wb97x-l-v`.
`omega`	float	`0.1`	Bohr⁻¹	Only for `wb97x-l-v`. Note the unit differs from `[mp2] omega`.

`[mp2]`

This section is shared by the whole MP2 family, ccsd, ccd, ccsd(t), linlccd, drpa, the double hybrids and tda/tddft, all of which read auxbasis and frozen_core from here. drpa, linlccd and a local rimp2 read nothing else from it (plus linlccd_variant for linlccd); any other [mp2] key on them is an error.

Key	Type	Default	Allowed values	Notes
`auxbasis`	string	`"cc-pvdz-ri"`; `"cc-pvdz-rifit"` for `tda`/`tddft`	aux basis name	The two defaults name the same bundled set (`cc-pvdz-rifit` is an alias of `cc-pvdz-ri`).
`frozen_core`	int, string or bool	`0`	integer ≥ 0, `"auto"`, `"none"`, `true` (= auto), `false` (= 0)	`"auto"` gives the standard small core for this molecule after the ECP is applied, and the run prints the resolved count.
`omega`	float	`0.420`	Å⁻¹	`att-rimp2` (erfc), `rs-mp2-rpa`. Ignored with a warning when `attenuator = "terf"`. An error on `att-rimp2` with `att_operator = "terfc"`.
`kappa`	float	none	κ > 0, Hartree⁻¹	κ-regularized MP2 for the exact `rimp2`; an error with `[local]`. Absent = plain MP2.
`c_os`	float	`1.2` (`scs-mp2`), `1.27` (`scs-mp2-2terfc`), `1.3` (`laplace-sos-mp2`)
`c_ss`	float	`1/3` (`scs-mp2`), `4.05` (`scs-mp2-2terfc`)		`laplace-sos-mp2` warns and ignores it.
`n_quad`	integer	`7`	`3` `5` `7`	`laplace-mp2`, `laplace-sos-mp2`. Any other value is an error.
`sos_formulation`	string	`"mo"`	`mo` `ao` `ao-sparse`	`laplace-sos-mp2`. `mo` and `ao` are exact and agree to round-off. `ao-sparse` is approximate and requires `domain_cutoff_bohr`.
`domain_cutoff_bohr`	float	none	> 0, Bohr	Required by `ao-sparse`. An error with the other formulations.
`formulation`	string	`"delta-lr"`	`delta-lr` `coupled-rings`	`rs-mp2-rpa`.
`attenuator`	string	`"erf"`	`erf` `terf`	`rs-mp2-rpa`. `terf` needs `FERRIC_TERF_TABLE_DIR`. An error on `att-rimp2` (use `att_operator`).
`r0`	float	`1.6828` (= 3.18 Bohr)	Å	`rs-mp2-rpa` with `terf` only. An error on `att-rimp2` (use `att_r0`).
`terf_omega`	float	linked, ω = 1/(r0√2)	Å⁻¹, > 0	`rs-mp2-rpa` with `attenuator = "terf"` only (an error elsewhere). Sets the terf/terfc sharpness independently of `r0`. Same as Python `run_rs_mp2_rpa(terf_omega=)`.
`att_operator`	string	`"erfc"`	`erfc` `terfc` (case-insensitive)	`att-rimp2` only (an error on any other kind). The short-range operator on the MP2 correlation; the SCF stays Coulomb. `terfc` is the Python `run_terfc_rimp2` and needs `FERRIC_TERF_TABLE_DIR`.
`att_r0`	float	`1.05`	Å, > 0	`att-rimp2` with `att_operator = "terfc"` only; an error with `erfc`.
`r0_sweep`	array of floats	none	Å, > 0	`rs-mp2-rpa` with `terf` only. Reuses one SCF for several r0 values. `r0` is then ignored with a warning.
`r0_bonded`	float	`0.75`	Å	`scs-mp2-2terfc`.
`r0_nonbonded`	float	`1.05`	Å, > `r0_bonded`	`scs-mp2-2terfc`.
`linlccd_variant`	string	`"hh"`	`hh` `drivers-only` `full`	`linlccd` only (an error on any other kind), exact and local alike: it selects the method. `drivers-only` equals RI-MP2; `full` adds the pp ladder (CCD-like VVVV memory). Any other value is an error.
`mp2v_r0`	float	`1.00`	Å, > 0	`mp2-v`. Also sets the VV10 damping r0. It is correlated with `mp2v_b` in the published fit.
`mp2v_b`	float	`11.0`		`mp2-v`.
`mp2v_c`	float	`0.0089`		`mp2-v`. Fixed in the paper. Changing it leaves the published parameterization.
`mp2v_attenuator`	string	`"terfc"`	`terfc` `erfc`	`mp2-v`. `terfc` needs `FERRIC_TERF_TABLE_DIR`. `erfc` is an unparameterized control.
`mp2v_omega`	float	linked, ω = 1/(r0√2)	Å⁻¹, > 0	`mp2-v` with `terfc` only. Setting it leaves the fitted parameterization.
`mp2v_vv10_damping`	string	`"terfc"`	`terfc` `none`	`mp2-v`. `none` double-counts short-range correlation.
`mp2v_nlc_n_radial`	integer	`50`	> 0	`mp2-v` VV10 grid.
`mp2v_nlc_n_angular`	integer	`50`	> 0	`mp2-v` VV10 grid (unpruned).
`oo_max_iter`	integer	`100`	≥ 1	`oo-rimp2` only (closed and open shell). Orbital-optimization iterations.
`oo_grad_conv`	float	`1e-4`	> 0	`oo-rimp2` only. Convergence threshold on the orbital-gradient norm.
`oo_level_shift`	float	`0.1`	Hartree, ≥ 0	`oo-rimp2` only. Level shift on the approximate diagonal orbital Hessian.
`oo_diis_size`	integer	`6`	≥ 1	`oo-rimp2` only. DIIS subspace for the orbital rotations. The four `oo_*` keys match Python `run_oo_rimp2(max_iter=, grad_conv=, level_shift=, diis_size=)`; on any other kind they are an error.

`[local]`

The local approximation of a correlated method. method.kind names the method (rimp2, drpa or linlccd); this section says whether and how its amplitudes are truncated. Without it (or with scheme = "none") the method is computed exactly. On any other kind the section is an error. The local runs are closed shell and task = "energy" only, and every printout and run-log result carries the model: "<method> (exact)" with "local": null, or the scheme, eps and kept fraction. See The MP2 family and Exact and local correlation.

Key	Type	Default	Allowed values	Notes
`scheme`	string	`"none"`	`none` `amplitude-threshold`	`amplitude-threshold`: drop pair amplitudes whose localized integral is at or below `eps` (single threshold). Any other value is an error.
`eps`	float	required with `amplitude-threshold`	≥ 0, finite	The threshold is part of the model and has no default. `0` keeps every amplitude and reproduces the exact method. An error with `scheme = "none"`.
`eps_sweep`	array of floats	none	each ≥ 0	`drpa` only. Several ε on one SCF and one localized assembly; sorted and de-duplicated, one result block per point. Instead of `eps`, not with it.
`reference`	bool	`false`		Also compute the exact method (canonical RI-MP2, canonical plasmon dRPA, exact LinLCCD) and print the local error against it. Costs the full exact calculation. An error with `scheme = "none"`.
`integral_direct`	bool	`false`		`rimp2` only. The integral-direct local MP2: never forms the global 3-index tensor.
`aux_radius`	float	`10.0`	Bohr, > 0	Integral-direct only (an error otherwise). Aux fit-domain radius.
`virt_radius`	float	`12.0`	Bohr, > 0	Integral-direct only. Virtual domain radius.
`ao_tail`	float	`1e-3`	≥ 0	Integral-direct only. `0.0` keeps every shell.
`schwarz_skip`	float	`1e-5`	≥ 0	Integral-direct only. Must be `0.0` for terfc operators, or the run errors.
`batch_merge`	integer	`4`	≥ 1	Integral-direct only.
`gate_cal`	float	none (gate off)	> 0	Integral-direct only. Pair-gate calibration (~0.7 Coulomb, ~0.02 erfc ω = 1).
`virt_schwarz_kappa`	float	none (off)	> 0	Integral-direct only. ε-linked Schwarz virtual-candidate screen.

`[rpa]`

Read by pdep-rpa, gw, bse-tda, tdhf-static-polarizability, and, for trunc_thresh only, rs-mp2-rpa.

Key	Type	Default	Allowed values	Notes
`auxbasis`	string	`"cc-pvdz-ri"`	aux basis name
`frozen_core`	int, string or bool	`0`	as `[mp2]`
`xc`	string	none (HF reference)	XC name	Switches the reference to RKS, or to UKS when open shell. Required by `tdhf-static-polarizability`. `bse-tda` ignores it. `pdep-rpa` with `task = "optimize"` uses an RHF reference; `xc` applies only to `task = "energy"`.
`n_quad`	integer	`20` (energy runs); `16` (`task = "optimize"`)		The Python `run_pdep_rpa` uses 40. Set it explicitly for reproducibility.
`quadrature`	string	`"gauss-legendre"`	`gauss-legendre` `gauss_legendre` `gl`; `minimax` `mini-max` `mm`; `chebyshev-tan` `chebyshev_tan` `chebyshev` `ct`
`u0`	float	`0.5`		Warn-and-ignore under `minimax`, which derives its own u₀.
`trunc_thresh`	float	`1e-4`; `0.0` (full rank) for `rs-mp2-rpa`		PDEP truncation.
`eigensolver_conv_thresh`	float	`1e-6` (energy); `1e-8` (`optimize`)		Alias: `davidson_conv_thresh`.
`chi0_sparsity`	string	`"dense"`	`dense`, `boys`, `boys:<thresh>`, `auto`, `auto:<cutoff>`, `auto:<cutoff>:<thresh>`, each boys/auto form optionally suffixed `@<radius_bohr>`
`run_diagnostics`	bool	`false`
`export_eigpot_prefix`	string	none		Writes `<prefix>_eigpot_NNN.cube`.
`export_eigpot_count`	integer	`10`		Capped at the number of eigenpotentials.
`cube_spacing`	float	`0.2`	Bohr
`cube_margin`	float	`4.0`	Bohr
`export_npz`	string	none	path	Turns on the NPZ property bundle. The `compute_*` keys below default to `true` only when this is set.
`compute_esp`	bool	`true`		ESP at the nuclei.
`compute_esp_surface`	bool	`false`		ESP on a vdW shell.
`esp_surface_vdw_scale`	float	`1.4`
`esp_surface_n_angular`	integer	`110`	Lebedev order
`compute_polarizability`	bool	`true`		`alpha_tensor`, the molecular static α.
`compute_alpha_atomic`	bool	`true`		`alpha_atomic`: the Krishtal–Senet–Van Alsenoy intrinsic per-atom α (JCP 125, 034312 (2006)), always Becke-partitioned; `c6_partition` does not affect it. Charge transfer between atoms is excluded; with `compute_polarizability` also on, the remainder `alpha_ct` = `alpha_tensor` − Σ_A `alpha_atomic` is exported.
`compute_electric_field`	bool	`true`
`compute_density_matrix`	bool	`true`
`compute_dipole`	bool	`true`
`compute_hirshfeld_charges`	bool	`true`		Proatoms are free-atom SCF densities in the molecule's basis and SCF settings, as in Python's `hirshfeld_charges`.
`compute_lowdin_charges`	bool	`true`
`compute_mulliken_charges`	bool	`true`
`compute_chelpg_charges`	bool	`true`
`compute_resp_charges`	bool	`true`
`compute_c6`	bool	`true`		With `c6_source = "pdep"`, also exports `alpha_ct_dynamic` (nfreq, 3, 3): molecular α(iω) − Σ_A α^A(iω).
`allow_partial_npz`	bool	`false`		By default a bundle missing a requested property fails the run.
`c6_source`	string	`"ts"`	`ts` `pdep` `mbd`
`c6_partition`	string	`hirshfeld` for `pdep`, `becke` for `ts`/`mbd`	`becke` `hirshfeld`

`[gw]`

Read by gw. bse-tda and tdhf-static-polarizability read frozen_core, and tdhf-static-polarizability also reads scissor. The [rpa] section supplies the screened interaction.

Key	Type	Default	Allowed values	Notes
`method`	string	`"g0w0"`	`g0w0` `cohsex` `evgw0` `evgw` (case-insensitive)
`qp_mos`	`[lo, hi]`	HOMO−2 … LUMO+2	absolute MO indices, half-open
`max_ev_iter`	integer	`20`		evGW/evGW0 outer loop.
`ev_conv_thresh`	float	`1e-4`	Hartree
`pade_npts`	integer	`0` (= `[rpa] n_quad`)
`qp_newton_damp`	float	`1.0`
`frozen_core`	int, string or bool	falls back to `[rpa] frozen_core`	as `[mp2]`	Also overrides the PDEP frozen core, so W and Σ agree.
`scissor`	float	`0.0`	Hartree	`tdhf-static-polarizability` only. At `0.0` some molecules hit a negative α diagonal and the run errors. The remedy is about 0.3–0.4 Ha.
`reference`	string	`"uhf"`	`uhf` `rohf` (case-insensitive)	`gw` on an open-shell molecule only: the reference is UHF or ROHF (UKS or ROKS with `[rpa] xc`). An error on a closed-shell molecule or another kind. Same as Python `run_u_gw(reference=)`.

`[tddft]`

Read by tda and tddft. Also set [mp2] auxbasis (see above).

Key	Type	Default	Allowed values	Notes
`n_roots`	integer	`3`
`xc`	string	none (HF reference: CIS or TDHF)	XC name	Selects the reference functional and the f_xc kernel. Meta-GGA, VV10 and range-separated functionals are refused.
`c_hf`	float	the functional's short-range exact-exchange fraction; `1.0` with no `xc`

`[optimize]`

Read when task = "optimize".

Key	Type	Default	Allowed values	Notes
`max_steps`	integer	`100`
`g_max_thresh`	float	`4.5e-4`	Hartree/Bohr
`g_rms_thresh`	float	`3.0e-4`	Hartree/Bohr
`e_conv`	float	`1e-6`	Hartree
`trust_radius`	float	`0.1`		Initial step size.
`coordinates`	string	`"cartesian"`	`cartesian` `cart`; `internal` `internals` `redundant-internal` `redundant_internal`

`[frequencies]`

Read when task = "frequencies".

Key	Type	Default	Allowed values	Notes
`hessian`	string	`"auto"`	`auto`; `analytic`; `fd` `finite-difference`	`auto` uses the analytic Hessian for RHF (closed shell) and UHF (aufbau occupations) with the Coulomb operator and exact four-centre J/K (no RI or COSX), a basis up to f functions and a libint2 with second derivatives; no ECP, external potential, implicit solvent, polarizable embedding, fractional occupations, MOM or constraints. Anything else uses finite differences. `analytic` is an error where it does not apply. The output prints `Hessian = analytic` or `finite-difference`.
`delta`	float	`5e-3`	Bohr, finite and > 0	Central-difference step, finite-difference Hessians only. Check the printed `Hessian asymmetry`: it is zero in exact arithmetic.

`[memory]`

Key	Type	Default	Allowed values	Notes
`budget_gb`	float	auto	finite and > 0	Precedence: this key, then `FERRIC_MEM_BUDGET_GB`, then the legacy `FERRIC_OOC_BUDGET_GB`/`FERRIC_ERI3_BUDGET_GB`, then 0.8 × available RAM, then 2 GiB. A value of 0, a negative value or NaN is an error; omit the key for auto. It bounds the ledgered allocations, not total process memory.
`three_index_budget_gb`	float	—		Deprecated alias. `budget_gb` wins if both are set.

`[output]`

Key	Type	Default	Allowed values	Notes
`json`	string or bool	`<input-stem>.ferric.jsonl` beside the input	a path, `true` (the default path), `false` (off)	On by default. See Run logs. `--json <path>` and `--no-json` override it.

`[qmmm]`

When present, the PQR supplies both the geometry and the MM charges. It cannot be combined with [external_potential]; doing so is an error.

Key	Type	Default	Allowed values	Notes
`pqr`	string	required	path	Geometry in Å and charges in e. The element is read from the atom name.
`qm_indices`	integer array	`[]`	zero-based	Use this, or `qm_seeds` + `qm_radius_angstrom`, but not both.
`qm_seeds`	integer array	`[]`	zero-based
`qm_radius_angstrom`	float	none	Å, > 0	Requires `qm_seeds`.
`link_bonds`	array of `[qm, mm]`	`[]`		Required when the cut crosses a covalent bond.
`boundary_scheme`	string	`"delete-host"`	`keep` `delete-host` `rc` `rcd`	Setting a non-default value without `link_bonds` is an error.

See QM/MM. Smeared PQR charges, polarizable sites and MM force fields are Python only. (Smeared charges outside QM/MM are available through [external_potential] with width.)

`[pcm]`

IEF-PCM implicit solvent (ferric-pcm). Absent means vacuum. Honoured on task = "energy" by rhf, uhf, rohf, ksdft and pdep-rpa (for pdep-rpa the RPA correlation is evaluated on the solvated reference). Any other kind, a gradient task (no gradient has a PCM term), [cosmo] in the same file, or pdep-rpa with [rpa] export_npz is an error. The solvent table and checks are shared with Python run_rhf(solvent=...). See examples/water-pcm.toml.

Key	Type	Default	Allowed values	Notes
`epsilon`	float	—	finite and > 1	Dielectric constant. Give exactly one of `epsilon` and `solvent`.
`solvent`	string	—	`water` (78.4) `dmso` (46.7) `methanol` (32.6) `ethanol` (24.9) `acetone` (20.7) `dichloromethane`/`dcm` (8.93) `thf` (7.43) `chloroform` (4.71) `toluene` (2.38) `hexane` (1.88), case-insensitive	Dielectric constants at 298 K. An unknown name is an error.
`lebedev_order`	integer	`110`	`6` `14` `26` `50` `110` `302`	Tesserae per atomic sphere.

`[cosmo]`

Conductor-like implicit solvent, applied to every SCF variant. It cannot be combined with [pcm].

Key	Type	Default	Allowed values	Notes
`epsilon`	float	required when the section is present	finite and > 1	`Default` in code is 78.39, but serde has no default for this key.
`radius_scale`	float	`1.17`	> 0	Multiplies Bondi radii.
`lebedev_order`	integer	`110`	6/14/26/50/110/302
`s_matrix_kind`	string	`"GaussianSmeared"`	`GaussianSmeared` `PointCharge`	Serde variant names, case-sensitive.

`[external_potential]`

Strict, like every other section: an unknown key here or inside a point charge is an error.

Key	Type	Default	Allowed values	Notes
`point_charges`	array of `{ q, x, y, z, width }`	`[]`	q in e; x, y, z in Bohr; `width` in Bohr, finite and > 0	Written as `[[external_potential.point_charges]]` tables. `width` is optional: with it the charge is Gaussian-smeared, density ∝ exp(−r²/width²) and potential q·erf(r/width)/r (the Python `smeared_charges=`); without it the charge is a point. See `examples/water-rhf-smeared-charge.toml`.
`field`	`[Ex, Ey, Ez]`	none	atomic units	Uniform electric field.

With both empty, the run is identical to a vacuum run.