# CFOUR_COORDINATES

> Specifies the type of coordinates used in the input file ZMAT. Value INTERNAL (=0) means that the geometry is supplied in the usual Z-matrix format, while CARTESIAN (=1) means that the geometry is given in Cartesian coordinates. A third option is XYZINT (=2) for which a Z-matrix connectivity is defined, but with values of the internal coordinates defined implicitly by supplying Cartesian coordinates. Note that geometry optimizations are currently only possible for INTERNAL and XYZ2INT. PSI4 Interface: Keyword set from active molecule, always CARTESIAN. Above restrictions on geometry optimizations no longer apply.

> - Type: string
> - Possible Values: INTERNAL, CARTESIAN, XYZINT
> - Default: INTERNAL