[input]¶
The [input] section defines the molecule, electronic-structure method, run
type, basis convention, and process-level threading. Most workflows require this
section.
Minimal Example¶
[input]
system=
O 0.000000000 0.000000000 -0.041061554
H -0.533194329 0.533194329 -0.614469223
H 0.533194329 -0.533194329 -0.614469223
charge=0
runtype=energy
method=hf
basis=6-31g*
Keywords¶
system¶
| Field | Value |
|---|---|
| Type | string or multiline coordinate block |
| Default | empty |
| Values | XYZ file path, or inline atom coordinates |
| Used by | all molecular workflows |
Defines the molecular geometry. When system is a single non-empty line, OpenQP
interprets it as a file path. When system= is followed by indented atom lines,
OpenQP reads those lines as inline coordinates.
Inline coordinates use one atom per line:
[input]
system=
O 0.000000000 0.000000000 -0.041061554
H -0.533194329 0.533194329 -0.614469223
H 0.533194329 -0.533194329 -0.614469223
Each atom line must contain at least symbol x y z. Numeric atomic labels are
also accepted by existing examples. When basis=library, each atom line must
also include a tag column.
system2¶
| Field | Value |
|---|---|
| Type | string or multiline coordinate block |
| Default | empty |
| Values | second XYZ file path, or second inline geometry |
| Used by | NACME and previous-geometry workflows |
Provides a second geometry. NACME uses it as the displaced or previous-step
geometry when [guess] file2 is not supplied.
charge¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 0 |
| Used by | electron count for all workflows |
Sets the total molecular charge. Keep charge, [scf] multiplicity, and the
chosen reference type physically consistent. When DFT-D4 is enabled, this same
charge is passed to DFT-D4's charge model; charged systems are therefore no
longer evaluated as neutral dispersion models.
method¶
| Field | Value |
|---|---|
| Type | string |
| Default | hf |
| Values | hf, tdhf, mp2, dftb, xtb |
| Used by | workflow dispatch |
Selects the electronic-structure driver. Use method=hf for HF and DFT
reference calculations. Use method=mp2 for standalone ground-state MP2
correlation. Use method=tdhf for TDHF, TDDFT, SF-TDDFT, MRSF-TDDFT, SOC,
NACME, and MRSF-EKT workflows. Use method=dftb for the OpenQP-DFTB
tight-binding backend (ground-state DFTB2, LC-DFTB2, and SF/MRSF-TDDFTB) and
method=xtb for the LC-GFN1-xTB backend; both are optional external libraries
that share the tight-binding dispatch and the SF/MRSF response plumbing
(development preview, not part of OpenQP 1.2.0).
DFT calculations still use method=hf; the functional is selected separately
with functional. MP2 calculations require functional to be empty.
functional¶
| Field | Value |
|---|---|
| Type | string |
| Default | empty |
| Used by | DFT and TDDFT-style calculations |
Selects a density functional. An empty value means Hartree-Fock. Examples use
values such as bhhlyp, pbe0, and DTCAM-series functionals where supported.
Some property implementations have functional restrictions. For example, NMR shielding does not support range-separated or meta-GGA functionals in the current checker.
Standalone MP2 uses an HF reference. With method=mp2, leave functional
empty; non-empty values are rejected before the calculation starts.
basis¶
| Field | Value |
|---|---|
| Type | string |
| Default | 6-31g* |
| Values | basis name, semicolon-separated per-atom names, or library |
| Used by | AO basis setup |
Sets the orbital basis. A single basis name applies to every atom:
basis=6-31g*
Per-atom basis names can be supplied in atom order with semicolons:
basis=aug-cc-pVDZ-PP;aug-cc-pVDZ
For tagged basis assignment, set basis=library, add a tag after each atom, and
define the tag mapping with library.
library¶
| Field | Value |
|---|---|
| Type | multiline string |
| Default | empty |
| Used by | tagged basis assignment when basis=library |
Maps atom tags to basis names:
[input]
system=
C 1.6062782722 1.5141391221 -1.8538091464 c1
H 0.7846511041 1.8564598303 -1.2260835006 h1
basis=library
library=
c1 6-31g
h1 6-31g*
When basis=library, every atom line must include a tag and every tag must have
a mapping.
runtype¶
| Field | Value |
|---|---|
| Type | string |
| Default | energy |
| Values | energy, grad, hess, nac, nacme, bp, optimize, meci, mecp, tci, mep, ts, irc, neb, prop, data, ekt, soc |
| Used by | top-level workflow dispatch |
Selects the calculation workflow.
Common values:
| Value | Meaning |
|---|---|
energy |
Single-point energy and requested properties. |
grad |
Energy plus gradient. |
hess |
Hessian and frequency workflow. |
nacme |
Nonadiabatic coupling matrix element workflow. |
soc |
Spin-orbit coupling workflow. |
ekt |
MRSF-EKT ionization/electron-affinity workflow. |
optimize |
Geometry optimization. |
meci, mecp |
Crossing-point searches. [optimize] meci_search=baeka makes MECI a two-or-more-state adaptive search. |
tci |
Legacy three-state adaptive-penalty runtype, retained unchanged for existing inputs. New BaekA calculations use runtype=meci with meci_search=baeka. |
ts, irc, neb, mep |
Reaction-path workflows. |
prop, data |
Multi-state property/data workflows for downstream drivers. |
Development preview
runtype=namd is added by OpenQP PR
#205. It is not
available in OpenQP 1.2.0. In that implementation branch, namd selects
surface-hopping molecular dynamics configured by the [md]
section and requires an MRSF-TDDFT setup.
When method=mp2, runtype must be energy. MP2 gradients, Hessians, and
optimization workflows are not wired in this release.
ispher¶
| Field | Value |
|---|---|
| Type | string mode |
| Default | auto |
| Values | auto, true, false |
| Used by | AO basis shell convention |
Controls pure spherical harmonic versus Cartesian AO shells.
| Value | Meaning |
|---|---|
auto |
Follow basis-set metadata where possible. |
true |
Force pure spherical shells, such as 5d and 7f. |
false |
Force Cartesian shells, such as 6d and 10f. |
Use this explicitly when reproducing a calculation from another program or when a workflow is validated for one convention.
d4¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | DFT-D4 dispersion correction |
Enables the DFT-D4 dispersion correction where supported. The input checker
requires a DFT functional when d4=true. By default, DFT-D4 loads the published
rational-damping parameters for that functional.
To supply an explicit rational-damping parameter set, provide all six values in
a [d4] section:
[input]
functional=pbe
d4=true
[d4]
s6=1.0
s8=0.95948085
s9=1.0
a1=0.38574991
a2=4.80688534
alp=16.0
[d4] keyword |
Meaning |
|---|---|
s6, s8, s9 |
two-body and three-body dispersion scale factors |
a1, a2 |
rational-damping length parameters |
alp |
three-body damping exponent |
The six values form one parameterization: specifying only a subset is an input
error. All values must be finite. In concise .oqp input the equivalent form is
d4(s6=1.0,s8=0.95948085,s9=1.0,a1=0.38574991,a2=4.80688534,alp=16.0).
soc_2e¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 1 |
| Values | 0, 1 |
| Used by | runtype=soc |
Controls whether mean-field two-electron SOC terms are included.
| Value | Meaning |
|---|---|
0 |
One-electron SOC terms only. |
1 |
One-electron plus mean-field two-electron SOC terms. |
The option lives in [input] because it gates the whole SOC workflow rather
than a response-solver detail.
Spin-orbit coupling is a relativistic interaction that mixes spin-free states of
different spin character. OpenQP's documented SOC workflow is an MRSF-TDDFT
workflow selected with runtype=soc; soc_2e=1 adds the mean-field
two-electron SOC contribution used in practical molecular SOC calculations.
Scalar relativistic DKH correction is a separate spin-free Hamiltonian option
controlled by [scf] scal_rel. See
References for OpenQP's relativistic
MRSF-TDDFT SOC method and mean-field SOC operator background.
Python style:
from oqp.openqp import OpenQP
job = OpenQP("soc_keywords")
job.molecule(geometry="water", charge=0)
job.theory.mrsf(functional="bhhlyp", basis="6-31G(2df,p)", nstate=12)
job.workflow.soc(soc_2e=1, scal_rel=2)
For Python SOC workflows, job.workflow.soc(...) sets [scf] scal_rel=2 by
default. Override it with scal_rel=0, 1, or 2 when needed.
qmmm_flag¶
| Field | Value |
|---|---|
| Type | boolean |
| Default | False |
| Used by | QM/MM dispatch |
Enables hybrid QM/MM calculations. When true, the QM region is embedded in a
classical (OpenMM) MM environment through the ESPF operator, configured by the
[qmmm] section. It applies to single-point QM/MM energies,
ground-state QM/MM molecular dynamics, and nonadiabatic
SOC-NAMD-QMMM dynamics (runtype=namd with
[md] soc=true). Without qmmm_flag=true the [qmmm] section is ignored.
Development preview
qmmm_flag and the [qmmm] schema documented here are from OpenQP PR
#205, not
OpenQP 1.2.0.
omp_threads¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 0 |
| Used by | OpenMP runtime setup |
Sets OpenMP threads per process or MPI rank. 0 means leave the environment or
compiled default unchanged.
Precedence is:
- command-line
--omp [input] omp_threadsOMP_NUM_THREADS- OpenQP built-in default
Example:
[input]
omp_threads=16
perf¶
| Field | Value |
|---|---|
| Type | integer |
| Default | 1 (recommended production) |
| Values | 0, 1, 2, 3 |
| Used by | the performance preset (see Performance) |
Opt-in performance preset that bundles the performance input keys into one
accuracy↔speed dial: 0 strict reference, 1 recommended production (exact),
2 faster (tiny degradation), 3 aggressive (small degradation allowed).
Explicit performance input keys override the preset. perf=-1 disables the preset.