Way back in the past when Einstein was the talk of the daily newpaper, Dirac initiated the idea that almost all chemistry problems where solve with the introduction of the quantum wave equation of Schrodinger. He said,
The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. It therefore becomes desirable that approximate practical methods of applying quantum mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation.
Around 1927, years after the introduction of the Schrodinger equation, Born and Oppenheimer introduced some approximation on the Schrodinger equation for many-electron system. This was the only solution to get away from the complexity of the equation. The main idea was to pretend that the nuclei were in its static configuration on the whole duration of the existence of the electron and let the electron do the motion. This reduces the Schrodinger equation down to the Hartree’s formulation of what is now known as Hartree equation.
This Hartree equation where then further improved with the addition of the anti-symmetry principle of electrons. With this was the introduction of a new term in the equation, now known as the exchange term capable of removing the unphysical quantities appearing in hartree equation. It became known as the Hartree-Fock equation, because of the contribution of Fock on this part. Fock, actually used group theory, while Hartree made it understandable for mere mortals. But it took a long time for the hatree-fock equation to be appecriated by the mere mortals. It was the advent of the digital computers that people started to notice the power of Hartree-Fock equation. Just like any other stuff, scientists were not contented with what HF equation can do. It poise some inaccuracy and some smart guys started playing with the idea of using density matrix instead of wavefunction as a unit of information container for the quantum system. The idea turn out to be a brilliant one,and the scientist, Kohn, Sham, and Hohenberg brought to the world the density functional method. Upon which, the wizards, Kohn and Sham was awarded a Nobel price in Chemistry (1998).
======= Way back in the past when Einstein was the talk of the daily newpaper, Dirac initiated the idea that almost all chemistry problems where already solved with the introduction of the quantum wave equation of Schrodinger. He said,
The underlying physical laws necessary for the mathematical theory of a large part of physics and the whole of chemistry are thus completely known, and the difficulty is only that the exact application of these laws leads to equations much too complicated to be soluble. It therefore becomes desirable that approximate practical methods of applying quantum mechanics should be developed, which can lead to an explanation of the main features of complex atomic systems without too much computation.
Introduction
Around 1927, years after the introduction of the Schrodinger equation, Born and Oppenheimer introduced some approximation on the Schrodinger equation for many-electron system. This was the only solution to get away from the complexity of the equation. The main idea was to pretend that the nuclei were in its static configuration on the whole duration of the existence of the electron and let the electron do the motion. This reduces the Schrodinger equation down to the Hartree’s formulation of what is now known as Hartree equation.
This Hartree equation where then further improved with the addition of the anti-symmetry principle of electrons. This lead to the introduction of a new term in the equation, now known as the exchange term capable of removing the unphysical quantities appearing in hartree equation.
This Hartree equation where then further improved with the addition of the anti-symmetry principle of electrons. With this was the introduction of a new term in the equation, now known as the exchange term capable of removing the unphysical quantities appearing in hartree equation. It became known as the Hartree-Fock equation, because of the contribution of Fock on this part. Fock, actually used group theory, while Hartree made it understandable for mere mortals. But it took a long time for the hatree-fock equation to be appecriated by the mere mortals. It was the advent of the digital computers that people started to notice the power of Hartree-Fock equation. Just like any other stuff, scientists were not contented with what HF equation can do. It poise some inaccuracy and some smart guys started playing with the idea of using density matrix instead of wavefunction as a unit of information container for the quantum system. The idea turn out to be a brilliant one,and the scientist, Kohn, Sham, and Hohenberg brought to the world the density functional method. Upon which, the wizards, Kohn and Sham was awarded a Nobel price in Chemistry (1998).