(Fig.1) Classical molecular mechanics can handle large molecules ?
Nobel prize was given to computational chemistry such as molecular mechanics ( or dynamics ) in 2013. Can we apply this new method in actual daily lives ?
Unfortunately, this Nobel-prize method is useless, forever.
This method can be used neither as ab-initio nor as chemical reaction ( this p.2 )
(Fig.2) This methods just fit the model to experiments, NOT predicting.
This new computational method, molecular mechanics uses some "classical approach" to calculate large molecules, which quantum mechanics cannot handle.
In fact, this molecular mechanics cannot predict any new physical values, because its model must rely on existing experimental values (= empirical ).
So this model's parameters must be adjusted in advance to fit experimental data. Molecular mochanics cannot be used to predict new chemical reactions.
(Fig.3) This classical method doesn't consider electrons. ← impractical.
This molecualr mechanics treats each atomic bond as classical spring or something. Of course, real atomic bonds are different from classical spring !
Surpridingly, this method ignores the existence of electrons ! Instead, it adjusts the classical spring constant (= fake ! ) depending on experimental data.
This method uses "virtual" classical potential (= force field, this p.9 ) where its potental energy is lower as the bond's length, angle are closer to "adjusted points".
(Fig.4) Parameters (= bond length, angle, torsion ) are adjusted artificially.
This molecular mechanis treats actual atomic bonds as "virtual" (= fake ) classical spring, ignoring electrons. Without considering electrons, how is it useful ?
All parameters (= bond length, angle, torsion .. ) used in molecular mechanics must be adjusted in advance to fit existing experimental data ( this p.9 ).
So this molecular mechanics needs a large number (= 106 ! ) of different parameters depending on different combinations of atomic bonds ( this p.5 ).
(Fig.5) Because its parameters depend on "existing" experimental data.
Molecular mechanics depends on "existing" experimental data, and ignoring actual electrons, so we cannot use this method to predict new chemical reactions.
Balanced bond length and angle used in potential fields are fixed in advance, so new bond breaking is impossible in molecular mechanics.
As a result, this computational method is useless forever despite getting Nobel prize.
(Fig.6) QM/MM (= quantum mechanics / molecular mechanics )
Quantum mechanics cannot handle large molecules, and molecular mechanics cannot be used for chemical reaction, so physicists try to combine them.
This new method is called "QM/MM" (= quantum mechanics / molecular mechanics ). Density functional theory (= DFT ) is often used in this p.4
But even this combined QM/MM remains useless, too, despite the media-hype.
Because quantum mechanical methods cannot solve muti-electron atoms, it just chooses artificial trial functions, so meaningless.
(Fig.7) No solution → just "choose" trial functions ! = useless
Schrodinger equation of two-electron helium contains interelectronic Coulomb energy. So it has No solution of helium.
All other multi-electron atoms including H2+ molecule ion have No exact solution. Then how does quantum mechanics deal with multi-electron atoms ?
Surprisingly, they just choose artifical trial function as "imaginary" solution.
"Choosing" convenient hypothetical solution out of infinite choices means Schrödinger equation has no ability to predict multi-electron atoms.
And it's impossible to try infinite kinds of trial wavefunctions and find the one giving the lowest energy in them.
(Fig.8) ↓ Variational method of Helium is impractical.
In the present useless quantum mechanics, they just guess and choose some trial function and adjust their free parameters to obtain desired energies in helium.
The problem is there are "infinite free choices" in this trial wavefunctions, so we cannot try all possibe wavefunctions to compare their energies.
It means finding the lowest ground state energy by trying infinite choices is impossible in quantum wavefunction !
All these trial function don't satisfy the total energy conservation, so "fake" energy, after all, meaningless.
The present use of "finite" basis set as approximate function never represents truth ( this p.4 )
(Fig.9) Electron interaction term is freely chosen. ← useless
In larger atoms in condended matter physics, density functional theory (= DFT ) is the only computing method.
It is often said this DFT is successful "ab-initio" method ( this p.3 ).
"Ab-initio" means first-principle which can predict values without empirical parameter ?
Unfortunately this DFT has No ability to predict any values, so useless.
Like this, DFT just chooses some convenient functional out of infinie choices.
In DFT, "exchange correlation functional" means interelectronic repulsions. This functional is unknown, can be freely determined ( this p.2 ).
So DFT can be considered a semi-empirical method, different from media-hype ( this p.23 ), and our basic science stops !
(Fig.10) Unknown exchange-correlation energy can be freely determined !
Density functional theory (= DFT ) does NOT have the standard "form" of interelectronic Coulomb energy and Pauli principle from the beginning.
So in DFT, physicists have to choose and determine "convenient form" of interelectronic repulsions out of infinite choices !
Artificially choosing convenient forms means DFT has NO ability to predict any physical values like ordinary Schrodinger equation !No functional (so far) is accurate for all properties of interest. No matter what functional is ‘invented’ someone will always find a case where it fails ( this p.17 ).
So DFT is one of empirical methods, NOT first-principle at all.
(Fig.11) Fatal cancer, HIV, ALS, dementia remain incurable.
If basic quantum mechanics remains useless and unrealistic, all other applied fields such as solid-physics and biology remain useless, too.
This is a serious problem, because it's impossible to cure fatal diseases such as cancer, HIV, ALS.. forever, as long as we believe fictional physics !
(Fig.12) Molecular mechanics with NO electrons is impractical, despite Nobel
New computational approach, molecualr mechanics was awarded Nobel prize in 2013. But this method contains NO real electrons !
All parameters in virtual classical model are artificially chosen in advance, so NO new chemical reactions can be predicted.
I'm afraid prestigious Nobel prize is exploited as a convenienet tool only to advertize greedy for-profit universities and fraudulent journals.
This tendency is very dangerous and harmful to science and young students !
2016/6/17 updated. Feel free to link to this site.