(Fig.1) ↓ Transistor IC, electrons are moving by "classical" electrodynamics
The media often argue that quantum mechanics is indispensable for computer transistor and smartphone. But it is a big lie.
Computer integrated circuits (= IC ) consist of transistors where each electron is actually moving obeying classical electrodynamics.
Quantum mechanics does NOT allow each electron to actually move.
Instead, quantum mechanics argues each electron splits into many places as vague "electron clouds" with No motion ! ← nonsense !
In transistors, each electron is moving as electric current, obeying classical concepts such as voltage and resistance, which are purely "classical mechanics".
In each transistor, electrons are controlled by "realistic" classical electrodynamics ( Not by quantum mechanics ).
By adjusting voltage, electric current flows or not, depending on the negative or positive potential. This is the basis of transistor.
No quantum mechanical concepts are found here. All these phenomena can be explained by classical mechanics.
(Fig.3) Quantum mechanics cannot deal with mulit-electron solids.
Schrödinger equation in quantum mechanics cannot deal with multi-electron atoms, molecules, solids.
So quantum mechanics replaced the whole solid crystals by abstract band theory ( this p.6 ).
In band theory, infinite electrons in semiconductor are replaced by One approximate pseudo-electron with fake mass (= this p.7 ).
This "fake" electron mass is called "effective mass", which is NOT the actual electron mass, can be negative, so unreal and useless ( this p.3 )
(Fig.4) ↓ These abstract models are really insulator, (semi)conductor ?
Insulator has very high resistance, and conductor has very low resistance. Semiconductor's resistance is between them.
Quantum mechanics tries to express these classical mechanical phenomena using abstract band model.
In band model conductor, electrons flow easily, because there is almost no energy gap between conduction and valence electrons.
In insulator, there is a wide energy gap between these two energy levels, so electrons cannot jump up to conduction area to cause electric current.
Semiconductor's energy gap is between them, controlled by impurity and other voltage in transistor. That's all.
These band theory in quantum mechanics is useless with NO ability to predict any new physical phenomena.
Because each time they get different experimental values such as resistance and electric current, they just artificially change fake mass and band gap to fit them.
(Fig.5) Human body, small bacteria are sophisticated nano-machines.
All quantum mechanics can do is replace actual solid by "fake band model" with fake electron mass.
Density functional theory (= DFT ) is an approximate Schrödinger equation used in solids, where physicists can freely choose convenient fake potential.
So all these quantum mechanical methods are meaningless and useless with NO ability to predict new physical values.
We already have technology to manipulate each atom. Old quantum mechanics blocks us from advancing from there !
The current computer is made through classical mechanical procedure, so it's much bigger than bacterial (= one of sophisticated nano-machines ).
If we define and use real atomic forces, we can realize sophisticated energy-efficient nano-machines minituarizing the present computer.
2017/3/3 updated. Feel free to link to this site.