geomeTRIC Optimizer Backend

OpenQP can use the geomeTRIC optimizer through [optimize] lib=geometric. The backend lets OpenQP provide energies and gradients while geomeTRIC performs coordinate updates.

Supported runtypes

Use [optimize] lib=geometric with:

• runtype=optimize: state-specific local minimum optimization.
• runtype=meci: minimum-energy conical intersection search using OpenQP's MECI objective.
• runtype=mecp: minimum-energy crossing point search using OpenQP's MECP objective.
• runtype=ts: transition-state optimization.
• runtype=irc: intrinsic reaction coordinate branch.

For runtype=ts and runtype=irc, OpenQP uses an initial Hessian (hessian=first) if [geometric] hessian=never is left at the default.

Basic minimum example

[input]
system=h2o.xyz
charge=0
runtype=optimize
basis=6-31g*
functional=bhhlyp
method=hf

[scf]
type=rhf
multiplicity=1

[optimize]
lib=geometric
istate=0
maxit=30

[geometric]
coordsys=tric
trust=0.1
tmax=0.3
convergence_set=GAU
prefix=h2o_geometric

Constrained optimization

geomeTRIC constraints can be provided with [geometric] constraints_file. Relative paths are resolved relative to the OpenQP input file.

[optimize]
lib=geometric
istate=0

[geometric]
constraints_file=scan.constraints
enforce=0.0
conmethod=0

IRC example

[input]
runtype=irc
method=hf
functional=bhhlyp
basis=6-31g*

[scf]
type=rhf
multiplicity=1

[optimize]
lib=geometric
istate=0
maxit=20

[geometric]
hessian=first
irc_direction=forward
prefix=hcn_irc_forward

Use irc_direction=backward for the reverse branch.

MRSF-TDDFT surfaces

For MRSF-TDDFT optimizations, use the normal MRSF reference settings:

[input]
method=tdhf
functional=bhhlyp
basis=6-31g*

[scf]
type=rohf
multiplicity=3

[tdhf]
type=mrsf
nstate=3

[optimize]
lib=geometric
istate=1

[geometric] keywords

Keyword	Default	Description
coordsys	tric	geomeTRIC coordinate system.
trust	0.1	Initial trust radius, in Angstrom.
tmax	0.3	Maximum trust radius, in Angstrom.
convergence_set	GAU	geomeTRIC convergence preset.
prefix	geometric	Prefix for geomeTRIC output files.
hessian	never	Initial Hessian option; TS and IRC use first automatically if left as never.
irc_direction	forward	IRC branch direction: forward or backward.
constraints_file	empty	geomeTRIC constraints file.
enforce	0.0	geomeTRIC constraint enforcement value.
conmethod	0	geomeTRIC constraint method.

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