Basic Keywords

To compute one-electron properties at a fixed geometry, the following keywords are common:

JOBTYPE = string

This keyword should be set to oeprop for PSI3 to compute electron properties. There is no default. For CI wavefunctions, limited properties such as dipole and transition moments may be evaluated directly in detci without having to specify JOBTYPE = oeprop.

WFN = string

Acceptable values are scf for HF, mp2 for MP2, detci for CI, detcas for CASSCF, and ccsd for CCSD. There is no default.

REFERENCE = string

Acceptable value are rhf and rohf. There is no default.

FREEZE_CORE = boolean

Specifies whether core orbitals (which are determined automatically) are to be excluded from the correlated calculations. Default is false.

PRINT = integer

The desired print level for detailed output. Defaults to 1.

MPMAX = integer

This integer specifies the highest-order electric multipole moment to be computed. Valid values are 1 (dipole), 2 (up to quadrupole), or 3 (up to octupole). Default is 1.

MP_REF = integer

This integer specifies the reference point for the evaluation of electric multipole moments. Valid values are 1 (center of mass), 2 (origin), 3 (center of electronic change) and 4 (center of the nuclear charge). For charge-neutral systems the choice of MP_REF is irrelevant. Default is 1.

GRID = integer

This integer specifies the type of one-electron property and the type of grid on which to evaluate it. The valid choices are

• 0 - compute nothing
• 1 - electrostatic potential on a 2-D grid
• 2 - electron density on a 2-D grid (spin density, if SPIN_PROP=true)
• 3 - projection of electron density gradient on a 2-D grid (spin density gradient, if SPIN_PROP=true)
• 4 - Laplacian of electron density on a 2-D grid (Laplacian of spin density, if SPIN_PROP=true)
• 5 - values of molecular orbitals on a 3-D grid
• 6 - electron density on a 3-D grid (spin density if SPIN_PROP=true)

Default is 0.

NIX = integer

The number of grid points along the x direction. This parameter has be greater than 1. Default is 20.

NIY = integer

The number of grid points along the y direction. This parameter has be greater than 1. Default is 20.

NIZ = integer

The number of grid points along the z direction (if a 3-D grid is chosen). This parameter has be greater than 1. Default is 20.

GRID_FORMAT = string

This keyword specifies in which format to produce grid data. The only valid choice for 2-D grids is plotmtv (format of plotting software program PlotMTV). For 3-D grids, valid choices are gausscube (Gaussian 94 cube format) and megapovplus (format of 3D rendering software MegaPOV+). The defaults are plotmtv and gausscube for 2-d and 3-d grids, respectively.

MO_TO_PLOT = vector

Specifies indices of the molecular orbitals to be computed on the 3-d grid. Indices can be specified as:

• unsigned integer - index in Pitzer ordering (ordered accoring to irreps, not eigenvalues). Ranges from 1 to the number of MOs.
• signed integer - index with respect to Fermi level. +1 means LUMO, +2 means second lowest virtual orbital, -1 means HOMO, etc.

All indices have to be either unsigned or signed, you can't mix and match, or you will get unpredictable results. Default is to compute HOMO and LUMO.

SPIN_PROP = boolean

Whether to compute spin-dependent properties. Default is false.

WRTNOS = boolean

If set to true, natural orbitals will be written to the checkpoint file. Default is false.