After all the atoms have been listed, enter a blank line. Next, list each variable with its corresponding value. Use a separate line for each variable. In some cases, where some of the variables are to be fixed as constants in a geometry optimisation, they are listed here after a blank line, rather than above with the real variables. End the Z-matrix with a blank line.
Notes See the following link for examples of how to define Z-matrices .
Note that, unlike molecular mechanics, there is no need for l to represent a real chemical bond, a a bond angle or da a torsion. Note that 0.0, 120.0, 180.0, etc. are sometimes used for the dihedral angles when these values are rigorously imposed by symmetry. Dummy atoms have the atomic symbol x and may be used as an aid in defining the Z-matrix. They are not included in the energy calculations.