Next: 13.3.1 Z-matrix input Up: 13 GEOMETRY SPECIFICATION AND Previous: 13.2 Symmetry specification


13.3 Geometry specifications

The geometry may be given in standard Z-matrix form, XYZ form, or cartesian and polar coordinate MOLPRO92 format. The geometry specifications are given in the form

geometry={,
options
atom specifications
}

The following are permitted as options:

Any valid combination of symmetry generators, as described in the previous section.
NOSYM
Disable use of symmetry.
ANGSTROM
Bond lengths specified by numbers, or variables without associated units, are assumed to be in Å.
CHARGE
Orient molecule such that origin is centre of charge, and axes are eigenvectors of quadrupole moment.
MASS
Orient molecule such that origin is centre of mass, and axes are eigenvectors of inertia tensor (default).
NOORIENT
Disable re-orientation of molecule.
PLANEXZ
For the $C_{2v}$ and $D_{2h}$ point groups, force the primary plane to be $xz$ instead of the default $yz$. The geometry builder attempts by swapping coordinate axes to place as many atoms as possible in the primary plane, so for the particular case of a planar molecule, this means that all the atoms will lie in the primary plane. The default implements recommendation $5a$ and the first part of recommendation $5b$ specified in J. Chem. Phys. 55, 1997 (1955). PLANEYZ and PLANEXY may also be specified, but note that the latter presently generates an error for $C_{2v}$.



Subsections

Next: 13.3.1 Z-matrix input Up: 13 GEOMETRY SPECIFICATION AND Previous: 13.2 Symmetry specification

P.J. Knowles and H.-J. Werner
molpro@tc.bham.ac.uk
Jan 15, 2002