XYZ — Optimization to proceed in Cartesian space.
This keyword requires that AMPAC runs the geometry optimization in Cartesian coordinates rather than the default internal coordinate system. If the geometry is provided to AMPAC in Cartesian coordinates, a full 3N coordinate optimization is executed in Cartesian space. By default, the geometry is reoriented to a z-matrix orientation but this can be avoided and the original Cartsian framework maintained by using this the ORIENT=ORIGINAL keyword. If the geometry is provided to AMPAC in internal coordinates, the keyword XYZ causes it to be converted to Cartesian coordinates, retaining the optimization flags, except for the first six which are set to zero, leading to a 3N-6 Cartesian geometry optimization. This allows an optimization to be run in a subset of the Cartesian coordinates.
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