*(Fig.1) Schrödinger equation for hydrogen atom = a proton + an electron*

Only Schrödinger equation for **one**-electron hydrogen atom can be solved and has exact solution.

Schrodinger equation gives the **constant** total energy equal to the sum of kinetic and potential energies.

*(Fig.2) ↓ Schrödinger equation Helium = two electrons (e-) + one nucleus (2e+)*

Schrödinger equation for **multi**-electron atoms such as Helium cannot be solved ! Helium atom consists of two electrons ( e- ) and one nucleus ( 2e+ ).

Helium's total energy E should be the sum of kinetic energy and Coulomb potential energy.

r_{1} ( r_{2} ) is the distance between the nucleus and electron 1 ( electron 2 ).

|r_{1} - r_{2}| is the distance between two electrons

*(Fig.3) You can choose any "fake potential" out of infinite choices in DFT !*

Schrödinger equation cannot give true solution. So to handle multi-electron atoms, they invented density functional theory (= DFT ).

This DFT calculation method is used in the applied fields such as condensed matter and protein interaction
DFT artificially changes "**multi**-electron Schrödinger equation" into **one**-electron density form and depends on "*fake* potential".

This fake potential is supposed to describe "electron-electron interaction", but its functional form (= V_{xc} ) is unknown.

You can **choose** *any* forms for this functional V_{xc} (= called "exchange-correlation" ) out of *infinite* choices. So DFT has **NO** ability to predict any physical values.

*(Fig.4) Multi-electron Couloum energy → fake potential in DFT, so meagninelss*

In condensed matter and solids including almost infinite atoms, computing by Schrödinger equation is far more **impossible**.

So physicists forcedly replaced multi-electron Schrödinger equation by one-electron DFT form which includes artificial **fake** potential.

There are **NO** restrictions in choosing this fake potential. You can pick up any form of fake potential V_{xc} out of infinite choices !

No matter what new "fake potential" is artificially invented, someone will always find a case where it fails ( this p.17 ).

DFT has **NO** ablity to predict any physical phenomena, so **useless** and meaningless. DFT is basically an "empirical" method ( this p.23 )

*(Fig.5) Now, almost all applied physics depends on useless DFT method. *

One-electron hydrogen atom is the **only** one in which Schrödinger equation can be applied. Almost all other applied physics depends on DFT.

This is the reason why the current condensed matter physics is **useless**, depending only on *unreal* quasipalrticles.

Physicists use this DFT method only for **publishing** their papers in science journals, **NOT** for practical use !

2017/2/10 updated. Feel free to link to this site.