OPT Keywords
| Keyword | Effect |
|---|---|
Algorithm bfgs|berny|rberny|sella|geometric | Optimizer backend (geometric aliases: geomet, tric) |
Coord cartesian|primitive|dlc|hdlc|tric|tric-p | Internal-coordinate model |
MaxCycle N | Maximum optimization cycles (default 100) |
Trust r | Initial trust radius, Bohr (default 0.3) |
TMax r | Maximum trust radius, Bohr (default 0.5) |
NoTrust | Disable TRM level-shifted Newton step |
TransitionState true | Search for a first-order saddle point (also: TS task token) |
IRC | Intrinsic reaction coordinate follow |
IRCDir +1|-1 | Restrict IRC direction |
NEB | Nudged elastic band |
Images N | Number of NEB images (default 8) |
SellaOrder 1|2 | Sella gradient order (1 = Hessian-only) |
Step trm|prfo|mmf | Step type (TRM, P-RFO, or MMF) |
Update bfgs|psb|ms|bofill|sr1|dfp|bfgs_powell|ts-bfgs | Hessian update formula |
Diis | Enable GEDIIS |
DiisSize N | GEDIIS subspace size |
Symmetry | Exploit point-group symmetry in IC build |
MOGuess true|false | Reuse previous cycle's orbitals as next SCF guess (warm start, default true) |
OptSymmetry | Enforce symmetry along the optimisation path |
NoStep | Run optimizer without taking a step (debug) |
Hessian analytical|semi | Hessian source for IC initialisation |
NoCartHessian | Ignore any inline Cartesian Hessian |
CartHessian … | Inline Cartesian Hessian matrix |
Rigid | Rigid-body component removal (TRIC only) |
RemoveTr | Remove TR modes (DLC/HDLC/TRIC only) |
ConMethod 0|1 | Delocalized construction method |
Connect | Reconnect connectivity graph at every step |
AddCart | Add Cartesian components to IC basis |
ConnectIsolated | Connect isolated fragments |
Primitive | Alias for Coord primitive |
PrimStep | Step projection in primitive IC space |
Gauss default|loose|tight | Convergence preset |
Tighten N | Tighten all criteria by 10⁻ᴺ |
MaxDisplacement r | Max allowed step length |
Constraints clause-list | Geometric constraints |
Dihedral true|false | (RBerny only) Include dihedral angles in IC set (default true) |
SuperWeakDih true|false | (RRust Berny only) Use super‑weak dihedral force constants (default false) |
EnergyNoise r | (RBerny only) Energy‑noise floor for trust‑radius updates (default 2e-8) |
Rust Berny backend keywords only apply when Algorithm rberny (or the RBerny task token) is active.
Constraint Syntax
Multiple clauses joined by ;:
Frozen atoms/components:
freeze_atoms:1-3;6freeze_x:2freeze_yz:4-5
Geometric targets (append ! for hard constraint):
bond:1-2=1.40angangle:1-2-3=104.5degdihedral:1-2-3-4=180deg!
Penalty tuning:
kbond=…,kangle=…,kdihedral=…, ork=…for all three
See OPT Section and Constraints for detailed descriptions and examples.