2.3. Basic Calculation Settings

2.3.1. Run Types

The type of calculation to be performed can be chosen via the simple input – for example, ! Opt – or via the RunTyp variable in %method:

%method
  RunTyp  Gradient  # Single point energy and gradient
end

The full list of available run types is given in Section 2.3.3. Note that some run types are triggered automatically under certain conditions and cannot be requested explicitly via the RunTyp keyword.

2.3.2. Method Classes

ORCA provides several classes of methods: Hartree–Fock (HF), Density functional theory (DFT), semi-empirical methods based on the NDDO approach, etc. This choice is controlled via the simple input, e.g. !HF, or via the method variable in the %method block:

%method
  method DFT
end

The list of available methods is given in Section 2.3.3.

2.3.3. Keywords

Table 2.4 Simple input keywords for basic calculation settings

Keyword	Description
Run types
Energy	Single point energy calculation (Default. Aliases: SinglePoint, SP)
EnGrad	Single point energy and gradient calculation (Alias: EnergyGrad)
Opt	Geometry optimization, see also Table 4.1
MD	Molecular dynamics simulation
CIM	Cluster-in-molecules calculation
PrintThermoChem	Thermochemistry calculation from previously calculated Hessian
PropertiesOnly	Compute properties from previously calculated densities
Docker	Host-guest docking
EDA	Energy decomposition analysis
NMScan	Deprecated! Normal mode scan (Alias: NormalModeScan)
NMGrad	Deprecated! Normal mode gradient (Alias: NMGradient)
MTR	Deprecated! Mode trajectory (Aliases: MT, ModeTrajectory)
Methods
HF	Hartree–Fock; RHF, UHF, and ROHF also set the wavefunction type
DFT	Density functional theory; RKS, UKS, and ROKS also set the wavefunction type
`	NDO-based method keywords are given in Table 3.22
<XTB-Method>	Native xTB-based method keywords are given in Table 3.27
MM	Molecular mechanics

Table 2.5 %method block input keywords for basic calculation settings.

Keyword	Options	Description
RunTyp								Energy	Single point energy calculation (Default. Aliases: SinglePoint, SP)
Gradient	Single point energy and gradient calculation
Opt	Geometry optimization (Aliases: Geom, Geometry, GeometryOpt)
Scan	Unrelaxed geometry parameter scan (Alias: Trajectory)
CIM	Cluster-in-molecules calculation
NMScan	Deprecated! Normal mode scan (Alias: NormalModeScan)
NMGrad	Deprecated! Normal mode gradient (Aliases: NMGradient, NormalModeGradient)
MTR	Deprecated! Mode trajectory (Aliases: MT, ModeTrajectory)
Method		HF	(Default) Hartree–Fock
DFT	Density functional theory
`	NDO-based method options are given in Table 3.23