keyword specifies the uses of molecular symmetry within the calculation. If symmetry
is in use, the molecule may be rotated to a different coordinate system, called
the standard orientation, before the calculation is performed. Derivatives
are then rotated back to the original (input) orientation. Orbitals are
printed in the standard orientation, and input for properties and background charge
distributions is required in the standard orientation.
keyword prevents the reorientation and causes all computations to be performed
in the Z-matrix orientation. By default, symmetry is used wherever possible to
reduce CPU, disk storage, and I/O requirements. Symmetry use can be completely
disabled by NoSymm, or modified by the Symm keyword and one or more
enables and NoInt disables use of integral symmetry (use of the "petite
list"). Synonymous with Int=[No]Symm.
NoGrad disables and Grad enables use of symmetry in integral derivative
NoSCF disables and SCF enables
use of N3 symmetry in SCF, which is used by default only for GVB calculations.
SCF=NoSCF is equivalent to Guess=LowSym
and combining all irreducible representations together.
Tells the program to use looser cutoffs in determining symmetry at the first point.
It is designed for use with suboptimal input geometries. Tight says to
use the regular criteria at the first point, and it is the default.
Try to follow point group/orientation during optimization.
Use no more symmetry than that found in the specified point group.
Specify axis to help specify subgroup.
Turn on symmetry when
it would otherwise be off, such as with massage. This can cause wrong answers,
so it should only be used if you know what you're doing!