[scf]¶
The [scf] section controls the reference wavefunction and SCF convergence
strategy. It is required for HF, DFT, TDHF/TDDFT, SF-TDDFT, MRSF-TDDFT, SOC,
NACME, and EKT workflows.
Minimal Examples¶
Closed-shell singlet:
[scf]
type=rhf
multiplicity=1
Triplet ROHF reference for MRSF-TDDFT:
[scf]
type=rohf
multiplicity=3
Keywords¶
type¶
| Field | Value |
|---|---|
| Type | string |
| Default | rhf |
| Values | rhf, rohf, uhf |
| Used by | reference selection |
Selects the SCF reference. Use rhf for closed-shell singlets, rohf for the
high-spin reference commonly used by SF/MRSF workflows, and uhf for
unrestricted references including UMRSF-TDDFT.
The input checker rejects type=rhf with multiplicity>1.
multiplicity¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 1 |
| Used by | spin state and electron occupation |
Sets the spin multiplicity, 2S+1. SF/MRSF examples usually use a triplet ROHF
reference with multiplicity=3.
In the high-level Python API, job.theory.mrsf(...) supplies this
usual MRSF reference multiplicity implicitly; set multiplicity in
job.molecule(...) for ordinary HF/DFT references or when overriding the
default deliberately.
maxit¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 30 |
| Used by | SCF iteration loop |
Maximum number of SCF iterations before failure or fallback handling.
conv¶
| Field | Value |
|---|---|
| Type | float |
| Default | 1.0e-6 |
| Used by | SCF convergence test |
Energy/density convergence threshold for the SCF cycle. Tighten this for high-precision properties or difficult state comparisons.
maxdiis¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 7 |
| Used by | DIIS subspace |
Maximum number of vectors kept in the DIIS extrapolation space.
diis_type¶
| Field | Value |
|---|---|
| Type | string |
| Default | cdiis |
| Values | none, cdiis, ediis, adiis, vdiis |
| Used by | DIIS convergence accelerator |
Selects the DIIS variant. cdiis is the default. vdiis can be useful for
difficult cases with level shifting.
diis_reset_mod¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 10 |
| Used by | DIIS reset logic |
Controls periodic DIIS reset behavior.
diis_reset_conv¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.005 |
| Used by | DIIS reset logic |
Convergence threshold used by the DIIS reset heuristic.
cdiis_switch¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.3 |
| Used by | CDIIS switching heuristic |
Threshold for switching into CDIIS-style extrapolation.
vdiis_vshift_switch¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.003 |
| Used by | VDIIS level-shift behavior |
Threshold for VDIIS/level-shift switching.
vshift¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.0 |
| Used by | virtual-orbital level shift |
Applies a level shift during SCF. Larger values can stabilize convergence but may slow final convergence.
incremental¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | True |
| Used by | incremental Fock build |
Enables incremental Fock builds where supported.
mom¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | maximum-overlap method |
Enables MOM occupation tracking for challenging electronic states.
mom_switch¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.003 |
| Used by | MOM activation heuristic |
Threshold controlling when MOM behavior is activated.
pfon¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | pseudo-fractional occupation number method |
Enables pFON smoothing for difficult SCF cases.
pfon_start_temp¶
| Field | Value |
|---|---|
| Type | float |
| Default | 2000.0 |
| Used by | pFON schedule |
Initial pFON electronic temperature.
pfon_cooling_rate¶
| Field | Value |
|---|---|
| Type | float |
| Default | 50.0 |
| Used by | pFON schedule |
Cooling rate used as pFON occupations are annealed.
pfon_nsmear¶
| Field | Value |
|---|---|
| Type | float |
| Default | 5.0 |
| Used by | pFON occupation smoothing |
Controls the smearing width/count used by the pFON method.
converger_type¶
| Field | Value |
|---|---|
| Type | string |
| Default | diis |
| Values | diis, soscf, trah, auto, ml |
| Used by | SCF convergence manager |
Selects the main SCF convergence strategy. auto and ml are Python-side
manager modes that choose a concrete native converger before dispatch.
init_converger¶
| Field | Value |
|---|---|
| Type | string |
| Default | None |
| Values | empty, none, diis, soscf, trah, auto, ml |
| Used by | initial SCF phase |
Overrides the converger used during an optional initial SCF stage.
alternative_scf¶
| Field | Value |
|---|---|
| Type | string |
| Default | trah |
| Values | diis, soscf, trah, auto, ml |
| Used by | fallback SCF attempts |
Fallback converger after repeated SCF difficulty.
escalation¶
| Field | Value |
|---|---|
| Type | comma-separated string |
| Default | empty |
| Values | diis, soscf, trah stages |
| Used by | custom fallback ladder |
Overrides the default escalation ladder. Example:
[scf]
escalation=soscf,trah
forced_attempt¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 2 |
| Used by | repeated SCF attempts |
Controls how many attempts the SCF manager can force before declaring failure or escalating.
init_scf¶
| Field | Value |
|---|---|
| Type | string |
| Default | no |
| Values | no, rhf, uhf, rohf, rks, uks, roks |
| Used by | initial low-cost SCF stage |
Requests an initial SCF calculation before the main SCF. KS-style initial SCF
values (rks, uks, roks) require [input] functional.
init_basis¶
| Field | Value |
|---|---|
| Type | string |
| Default | none |
| Used by | initial SCF basis selection |
Basis used for the initial SCF stage. library can be used with
init_library.
init_library¶
| Field | Value |
|---|---|
| Type | multiline string |
| Default | empty |
| Used by | tagged basis mapping for init_basis=library |
Maps atom tags to basis names for the initial SCF basis.
init_it¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 15 |
| Used by | initial SCF stage |
Maximum number of iterations in the initial SCF stage.
init_conv¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.001 |
| Used by | initial SCF stage |
Convergence threshold for the initial SCF stage.
save_molden¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | True |
| Used by | Molden output |
Writes Molden orbital files when supported.
rstctmo¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | MO ordering |
Restricts molecular-orbital ordering in workflows that need stable state or orbital labels.
scal_rel¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 0 |
| Values | 0, 1, 2 |
| Used by | scalar-relativistic one-electron Hamiltonian |
Selects the scalar relativistic Douglas-Kroll-Hess correction applied to the spin-free one-electron core Hamiltonian:
| Value | Meaning |
|---|---|
0 |
Disabled. |
1 |
First-order Douglas-Kroll-Hess correction. |
2 |
First- and second-order Douglas-Kroll-Hess correction. |
This is not the SOC switch. scal_rel changes the scalar, spin-free
Hamiltonian; SOC is selected separately with [input] runtype=soc and
[input] soc_2e. See References
for the DKH background.
The input-file default is scal_rel=0. In the high-level Python API,
job.workflow.soc(...) sets scal_rel=2 by default for the SOC workflow
because the documented SOC path uses a DKH2 spin-free Hamiltonian before the
SOC matrix is formed. Pass scal_rel=0, 1, or 2 to override that helper
default.
stability¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | SCF stability analysis |
Requests stability analysis where wired.
soscf_lvl_shift¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0 |
| Used by | SOSCF convergence |
Level shift used by the SOSCF converger.
verbose¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 1 |
| Used by | SCF logging |
Controls SCF verbosity.
TRAH Keywords¶
TRAH is the trust-region augmented Hessian SCF converger. The package build uses the native TRAH implementation by default when TRAH is requested.
trh_impl¶
| Field | Value |
|---|---|
| Type | string |
| Default | auto |
| Used by | TRAH implementation selection |
Selects the TRAH implementation. auto uses the available implementation and
falls back to native behavior when external OpenTRAH is absent.
trh_stab¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | TRAH stability mode |
Enables TRAH stability behavior.
trh_ls¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | TRAH line search |
Enables line search inside TRAH.
trh_sub_solver¶
| Field | Value |
|---|---|
| Type | string |
| Default | davidson |
| Used by | TRAH micro-iteration solver |
Selects the subsystem solver used by TRAH.
trh_nrtv¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 1 |
| Used by | TRAH random trial vectors |
Number of random trial vectors used in the TRAH subsystem.
trh_r0¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.4 |
| Used by | TRAH trust radius |
Initial TRAH trust radius.
trh_jd_start¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 30 |
| Used by | TRAH Jacobi-Davidson switch |
Iteration threshold for the Jacobi-Davidson path in TRAH.
trh_nmic¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 50 |
| Used by | TRAH micro-iterations |
Maximum number of TRAH micro-iterations.
trh_gred¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.001 |
| Used by | TRAH global reduction |
Global reduction factor for the TRAH microproblem.
trh_lred¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.0001 |
| Used by | TRAH local reduction |
Local reduction factor for the TRAH microproblem.