Site Designed: By Daniel Burbridge, School of Chemistry, University Of Bristol
The differences between ab-initio and semiemperical models:
Semiempirical methods neglects some of the more time consuming mathmatical terms in the Schrodinger equation by compensating for them using parameters. These parameters can be deduced experimentally or by performing ab initio calculations on model systems. Ab initio methods include all terms.
Approximation of the wavefunction:
All modern methods for approximation use the Hartree-Fock (HF) self-consistent field approach to solving the molecular wave equation (both ab initio and semiempirical.) The difference being that semiempirical methods neglect to solve specific integrals in the HF equation.
