[hess]¶
The [hess] section controls Hessian, frequency, and thermochemistry
workflows.
Keywords¶
type¶
| Field | Value |
|---|---|
| Type | string |
| Default | numerical |
| Values | numerical, analytical |
| Used by | Hessian dispatch |
Selects numerical finite-difference or native analytical Hessian dispatch.
Analytical Hessians are validated for supported HF/DFT ground-state cases. The
input checker requests type=numerical when the method, state, or basis is
outside the analytical path.
state¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 0 |
| Used by | Hessian target state |
HF/DFT Hessians use state 0. TDHF-family Hessian workflows use positive
excited-state indices.
dx¶
| Field | Value |
|---|---|
| Type | float |
| Default | 0.01 |
| Used by | numerical Hessian displacement |
Finite-difference step size for numerical Hessians.
nproc¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 1 |
| Used by | numerical Hessian workers |
Worker count for numerical Hessian calculations. Must be at least 1.
read¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | Hessian restart/input |
Reads an existing .hess.json sidecar where the workflow supports it. Current
sidecars carry a versioned state/model-configuration signature and the atom,
geometry, and isotopic-mass identity. OpenQP rejects unsigned older files or mismatches rather
than silently reusing a Hessian or vibrational data from another calculation;
rerun with read=False to generate a current sidecar.
restart¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | numerical Hessian restart |
Continues an interrupted numerical Hessian workflow.
Native TS/IRC drivers reject restart=True while their displaced-gradient
artifacts lack geometry/model signatures. Use it only for the standalone
numerical Hessian workflow; native TS/IRC initial Hessians are recomputed.
temperature¶
| Field | Value |
|---|---|
| Type | float list |
| Default | 298.15 |
| Used by | thermochemistry |
Temperature or temperatures, in Kelvin, for thermochemical analysis. Values must be positive.
clean¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | temporary Hessian files |
Removes temporary Hessian files where supported.
symmetry_unique¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | numerical Hessian displacements |
When enabled for a symmetric molecule, displaces one atom from each symmetry-equivalent atom orbit and reconstructs the remaining numerical Hessian rows with the detected abelian symmetry operations. OpenQP detects the point group again at the current reference geometry and proves atom-orbit coverage before launching displaced-gradient jobs.
If symmetry is absent, detection fails, the tolerance is too loose relative to
dx, or complete orbit coverage cannot be established, OpenQP reports the
reason and safely uses the full displacement set. The option does not enable
integral symmetry reduction in the displaced child calculations.