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Molecular dynamics is useless
(Fig.1) Ab-initio MD just changes coefficients (= c ) of artificially-chosen fake electron's wavefunction lacking real atomic shape.
Due to unphysical quantum mechanical wavefunction lacking real atomic shape, today's only molecular simulating method called ( classical ) molecular dynamics (= MD ) is impractical, too time-consuming to calculate each atomic position at short-time intervals many, many times, based on artificially-chosen force field potential.
Ab-initio or first-principle molecular dynamics (= AIMD, FPMD, CPMD ) changing fictitious electron's wavefunction based on DFT pseudo-potential is much more impractical and more time-consuming than the impractical classical MD ( this-p.2-left-1st-paragraph, this-p.2-I-introduction, thisp.19-3rd-paragraph ).
In Ab-initio MD, quantum mechanics has to treat the whole atoms as one pseudo-electron DFT (= Kohn-Sham ) model through artificially-chosen exchange pseudo-potential (= functional ) that is fake ab-initio (= empirical ), unable to predict any physical values ( this-p.2-2nd-paragraph, this-p.2-left-last-paragraph~p.2-right, this-p.23-lower ).
In this impractical ab-initio MD, only nuclei (= positive ions ) are treated like classical particles, moved gradually by differentiating the total fake energy E with respect to each nuclear coordinate RI (= force = space derivative of total potential energy, this-p.6 ) at short-time intervals.
In Born-Oppenheimer (ab-initio) molecular dynamics (= BOMD ), they have to artificially choose fake one-pseudo-electron DFT wavefunction ( this-p.14-(40) ), and update their coefficients (= c ) by the extremely time-consuming self-consistent field (= SCF ) method at short-time intervals ( this-p.23,p.27,p.32 ). which is completely impractical ( this-p.35, this-p.2 ).
So ab-initio MD often uses the slightly simpler Car-Parrinello molecular dynamics (= CPMD ) using fictitious electron's mass μ ( this-p.36, this-p.9, this-p.7,22 )
↑ In this CPMD, they update each coefficient (= c ) of the artificially-chosen pseudo-electron's wavefunction (= φ = basis set ) by differentiating the total energy E with respect to the coefficient c ( this-p.41,p.44, this-p.12-(6.10), this-p.5,p.7 ) at extremely short-time intervals (= 0.1 fs, this-p.12-22, this-p.3,p.12 ) together with updating nuclear positions.
So ab-initio molecular dynamics just changes fictitious electron (fake) wavefunction's coefficients instead of moving real electrons.
And this ab-initio MD (= CPMD, BOMD.., old Ehrenfest MD is not used now, this-13-upper ) needing calculations of both nuclear and fictitious electron's states at much shorter time intervals (= 0.1fs ) is more impractical and more time-consuming than classical MD updating only atoms at the intervals of 2fs ( this-p.19-lower, this-p.2 ).
The 4th-last and last paragraphs of this hyped news (7/8/2025) say
"Throughout this research, ..the team have investigated the vibrational properties of titanium nitride using Raman spectroscopy, a non-destructive chemical analysis technique which provides detailed information about chemical structure."
"The ultimate goal of this project is to gain an atomistic-level understanding of the role played by the atoms" ← This means the atomistic-level understanding still has Not been achieved.
↑ Raman spectroscopy's resolution (= just measuring light reemitted from the material ) is about 1μm ( this-middle-Raman is used for microscopic, this-resolution ), which can Not distinguish single atoms of less than 1nm, nor clarify the atomic mechanism.
↑ This research paper ↓
p.1-abstract says "but a fundamental understanding of how their structures evolve during electrocatalysis remains unknown" ← quantum mechanics failed to clarify the material's atomic mechanism.
p.4-left-computational methods used the impractical ab-initio molecular dynamics based on unreal DFT's pseudo-potential, which can Not clarify real atomic mechanism.
(Fig.S) Quantum mechanical DFT just artificially choosing (fictitious) spin parameters cannot predict ferromagnet or antiferromagnet. → No evidence of spin
Ferromagnet or antiferromagnet is said to be caused by (fictitious) electron spin according to quantum mechanics.
But an electron is known to be Not actually spinning.
Furthermore, quantum mechanics just choosing free spin parameter J has No ability to predict ferromagnet or antiferromagnet.
Quantum mechanical Schrodinger equations are unsolvable and unable to predict any multi-electron atoms or molecules.
Quantum mechanics has to rely on the rough approximation called density functional theory (= DFT ) that tries to treat the whole material as one-pseudo-electron or quasiparticle model with artificially-chosen pseudo-potential (= different exchange-correlation functionals give different spin interaction parameter J as shown in this p.7-Table.III ).
In this mainstream DFT, physicists have to choose various freely-adjustable parameters such as fictitious wavefunctions, exchange-correlation-pseudo-potential (= U, J, this p.6-right-1st-paragraph, this-p.1-right-last ), (spin) magnetic moment (= m, this p.4~p.7, this p.136(p.128)-2nd~3rd-paragraphs ), and numbers of electrons (= n ) in different spin states ( this p.16-1st-paragraph ). ← No quantum mechanical prediction
This p.11-3rd-paragraph says
"In practice treated as fitting parameters, i.e., adjusted to reach agreement with
experiment: equilibrium volume, magnetic moment, band gap"
↑ Instead of (useless) quantum mechanical prediction, these artificially-chosen magnetic moment parameter (= m ), electron spin number (= n or spin polarization parameter ζ ) determine whether the material is ferromagnet or antiferromagnet ( this p.53(p.45),p.60-63, this p.8-p.12. p.21(or p.20) ).
DFT's exchange-potential and pseudo-potential parameters (= U, J ) must be chosen from experimental results in most cases (= instead of being predicted by quantum mechanics, this p.4-right-3rd-last-paragraph, this p.2-left-2nd-last-paragraph, this p.3-1, this p.3, this p.22 chose t or J, this p.6-right-1st-paragraph ).
This p.5-right says
"However, apart from the intentionally fitted
LSDA+U result, all functionals overestimate the antiferromagnetic coupling J by at least a factor of two, and perform
even worse for the interchain coupling J ( this p.16, this p.8-left-1st-paragraph )"
So quantum mechanics (= unphysical spin model ) relying on various freely-chosen parameters ( this p.10, this p.21 ) cannot predict whether the material is ferromagnetic or antiferromagnetic ( this p.22(or p.21)-2nd-paragraph ), which means there is No evidence that (anti-)ferromagnetism is caused by electron spin.
This research paper ↓
p.30(or p.29)-3rd-paragraph says "The treatment described electrons in a non-interacting, fictitious potential"
p.47(or p.46) says " The most straightforward inclusion of magnetic materials in DFT is to attach two spinors ( χ+ and χ−) to the wave function (= artificially-chosen fake wavefunctions for expressing unreal spin )"
p.95(or p.94)-Table 4.7 exchange (spin) interaction parameters J are different among different chosen exchange-correlation (= XC ) potential functionals such as LDA, PBE, rSCAN.. ( this-p.6, this-3rd-paragraph ), ← Spin exchange parameters affected by the artificial choice of exchange potential means the spin magnetic moments are Not quantum mechanical prediction.
p.96(or p.95)-3rd-paragraph says "DFT is known to overestimate the magnitude of the exchange interaction parameter"
p.126(or p.125)-2nd-paragraph says "the magnetism within iron arsenide depends heavily on the choice of XC (= exchange-correlation ) functional"
Stable ferromagnet is caused by the realistic electron's orbits (= instead of spin ) meshed with each other by Coulomb electric interaction.
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