Key Points for Z-Matrices:

Z-Matrices

Students

• Computational chemistry programs require scientists to specify two things in order to run an input file:
  1. Basis Set
  2. Cartesian Coordinates
• It is important for scientist to identify the correct molecular geometry because small changes in geometry cause large changes in the molecular energy.
• There are three methods that scientists use to calculate molecular geometries:
  1. Calculate cartesian coordinates by hand (only works for small molecules)
  2. Graphical User Interfaces (GUI) programs that calculate the geometry for the users.
  3. Z-Matrices - converts the bond angles, bond lengths, and dihedrals of each atom into cartesian coordinates