The Trident Computational Methods. Trident provides a targeted set of computational methods, addressing the needs of medicinal chemists. All methods are easily accessed via Trident's seamless graphical interface.
  Molecular Mechanics Molecular mechanics is presently the only practical method for calculations on very large molecules or for conformational searching on molecules with a large number of degrees of freedom. MMFF94, in particular, has proven to be a reliable and fast tool for conformational analysis. There are no atom limits for molecular mechanics calculations.

Trident molecular mechanics calculations also include optional aqueous solvent energy corrections.
Molecular Orbital
Semi-empirical models are the simplest of the quantum chemical schemes, and are useful for equilibrium and transition-state structure calculations. PM3, in particular, has proven to be a reliable tool for geometry calculations on transition metal inorganic and organometallic compounds.

Trident includes PM3 methods with parameter extensions for heavy main-group elements for most transition metals.
Molecular Orbital
Hartree-Fock models are well documented standards for predicting structure, energy and property calculations, in particular for organic molecules.

Trident provides two versatile basis sets: 3-21G and 6-31G*.