It is suited for use on vector machines. A variety of methods of specifying the molecular geometry exists. The program utilizes s,p, d and f Gaussian basis sets, and there is an extensive basis set library. Energy calculations are available for a variety of CI wave functions. Two algorithms are available for determining equilibrium and transition state geometries.
Geometry optimizations can be complete or constrained and use Cartesian or internal coordinates.
The analytic MP2 algorithm is highly vectorized. The force constant matrices yield vibrational frequencies and may be combined with dipole moment and polarizability derivatives to give infrared and Raman intensities. The study of vibrational circular dichroism is also possible. Density Functional Theory has been included in the latest edition of the program. Other features include the calculation of dipole and quadropole polarizabilities, with frequency dependence, magnetizabilities, hyperpolarizabilities and NMR shielding constants.