12  Ab initio Method/First Principle Calculation  Based on Solution of Schrödinger Equation  Works well for H atom only. For all other atoms, approximations are needed  Robert Parr (Caltech)  1950  [288]  
13  Hartree Fork Method and Slater Determinant  Uses the variational theorem (which is wavefunction based approach using mean field approximation)  Approximate solution is obtained. It is a form of Ab initio method. 

 [289]  
14  Evolution of Hartree Fork Method  SelfConstrained Field (SCF) Method  Evolution of HF Method  Approximate solutions 

 [289] 
MøllerPlesset (MP) perturbation (MP 1)  Hamiltonian is divided into two parts $\widehat{H}={\widehat{H}}_{0}+\lambda \widehat{V}$ and solved  ψ and energy are HF ψ and HF energy 

 [289]  
MP 2  ψ remain same, energy is changed  ψ is treated by the help of summations 

 [289]  
Density Functional Theory (DFT)  Energy of system is obtained from electron density  Approximation based 
 1996  [290] [291] [292]  
15  Interatomic Potential  Explain Interaction of atoms in a system in terms of potentials  Limited by Accuracy, Transferability and Computational Speed of System  Multi (Many) Body Potentials Daw Baska (Sandia National Labs)  1984  [293] 