The first implementation of a theory — no experimental fitting, no empirical parameters, just fundamental constants and equations.

This is where Ab Initio versions diverge from standard language learning. The curve is exponential.

The Hartree-Fock method is a self-consistent field (SCF) approach that assumes that the wavefunction of the system can be approximated as a single Slater determinant. Post-Hartree-Fock methods improve upon the Hartree-Fock method by including electron correlations through perturbation theory or configuration interaction. DFT, on the other hand, is a method that uses the electron density to describe the system, rather than the wavefunction.

Over the years, several versions of ab initio methods have been developed, each with its own strengths and weaknesses. Some of the most popular versions include:

In conclusion, ab initio methods are a powerful tool for studying complex systems and phenomena in chemistry, physics, and materials science. The different versions of ab initio methods, including Hartree-Fock, post-Hartree-Fock, coupled cluster, and density functional theory methods, offer a range of approaches for solving problems from first principles. The applications of ab initio methods are diverse and continue to grow, enabling researchers to investigate complex systems and phenomena with unprecedented accuracy. As computational power continues to increase, ab initio methods will play an increasingly important role in advancing our understanding of the behavior of molecules, solids, and liquids.