Next: Hydrogen Bond Properties, Up: Table Properties

All the internal coordinate tables (`BOND`, `ANGLE`,
`TORSION`, and `IMPROPER`) have the same set of properties. The
syntax for these properties is as follows:

{GEOMETRY} property ::= { ENERGY } { NUMBER }

The `GEOMETRY` property returns the geometry of the internal
coordinate. For example the `BOND` `GEOMETRY` is the bond
length; the `TORSION` `GEOMETRY` is the torsion angle. The
`ENERGY` property returns the energy of the the internal coordinate.
For example, `IMPROPER` `ENERGY` returns the energy of the
improper torsion angles. The `NUMBER` property returns the
sequential position of the internal coordinate in the list contained in
the PSF. For example, the numbers of the sulfur-sulfur bonds in a
cysteine bridge will be very large, because they are added last. The
`NUMBER` property is useful in figuring out error messages from the
energy routines as the numbers the energy routines output correspond to
the numbers returned by this property.