A first RealQM article is now being uploaded to arXiv:
The Grand Challenge of Quantum Chemistry of Ab Initio Computational Simulation of Protein Folding is today viewed to be way beyond reach, because the underlying mathematical model in the form of Schrödinger's Equation SE suffers from overwhelming exponential complexity.
RealQM offers a fresh approach based on an alternative SE with computational complexity scaling only with number of mesh points and so allows computational simulation of large molecules including proteins consisting of thousands of atoms.
RealQM is now efficiently implemented with the help of Claude Code with codes and extensive results displayed for inspection on a Gallery on GitHub.
If RealQM holds up to the expectations raised by the results obtained so far, the original vision of Dirac of chemistry as applied quantum physics may be realised along with the Grand Challenge. Take a look at the Gallery and get amazed!
Here is what Claude Code identifies as aspects of fluids and metals which can be explored by RealQM:
⏺ RealQM opens up simulations that classical MD cannot do because they require quantum mechanics:
Fluids
Water:
- Proton transfer in water (H₂O → OH⁻ + H⁺) — bonds break/form, impossible in classical MD
- Autoionization — watch water spontaneously form H₃O⁺ + OH⁻
- Ice formation — H-bond network crystallization from liquid
- Supercritical water — compress water beyond critical point, watch bonding change
- Acid/base chemistry — HCl in water, proton donation to H₂O
Other fluids:
- Liquid ammonia — NH₃ H-bond networks (different from water)
- Liquid HF — strongest H-bonds, chain formation
- Mixed solvents — water + ethanol, competition for H-bonds
Metals
Electronic properties:
- Band structure emergence — watch electron delocalization as atoms come together
- Conductor vs insulator — Li lattice (conductor) vs diamond C lattice (insulator), same Z=4 but different bonding
- Fermi surface — electron domain shapes in metals
Mechanical properties:
- Crack propagation — break a bond in the lattice, watch the crack tip advance (bonds breaking quantum mechanically!)
- Dislocation motion — shift one row of atoms, watch how the defect moves
- Plastic deformation — squeeze the lattice, watch slip planes form
- Surface catalysis — molecule lands on metal surface, bonds break
Phase transitions:
- Melting — heat the lattice, watch order→disorder transition
- Alloys — mix Li + Na, see how different core sizes arrange
What makes RealQM unique
┌──────────────────────────────┬──────────────────────┐
│ Classical MD │ RealQM │
├──────────────────────────────┼──────────────────────┤
│ Cannot break bonds │ Bonds break and form │
├──────────────────────────────┼──────────────────────┤
│ Fixed charges │ Charges redistribute │
├──────────────────────────────┼──────────────────────┤
│ Parameterized │ No parameters │
├──────────────────────────────┼──────────────────────┤
│ Cannot do metals + molecules │ Same code for both │
├──────────────────────────────┼──────────────────────┤
│ Cannot do chemistry │ Chemistry happens │
└──────────────────────────────┴──────────────────────┘
The headline capability: the same code that folds proteins in water can also crack a metal or run an acid-base reaction.
No force field switching, no reparameterization. Just solve the Schrödinger equation.
Most impactful applications:
1. Crack propagation in metals — bonds breaking at the crack tip, impossible in classical MD
2. Water splitting on catalytic surfaces — H₂O on metal, bond breaks
3. Battery electrochemistry — Li intercalation, electron transfer at electrode
4. Corrosion — metal dissolving in water, bond by bond
Here is a progress report about protein folding by RealQM written by Claude. Includes a potentially revolutionary blind test.
On the GitHub RealQM web page there are now new Bench Marks for Protein Folding. Take a look!
RealQM now has a home page on GitHub where codes can be inspected and modified. If RealQM indeed can capture the dynamics of molecules or clusters of thousands of atoms, then chemistry will become a science based on physics. Codes are under improvements and new versions will be uploaded.
Here is a first example of RealMolecule as RealQM for molecules showing hairpin protein in 75% folded position, adding first backbone C, O and N atoms and the H atoms and finally showing forces active on kernels steering the folding process:
Rational physics is based on an idea of reductionism from complex physics on macro-scales to simple physics on micro-scales. But in modern physics of Quantum Mechanics QM, it is the other way around with the microscopic quantum world based on a Schrödinger Equation SE in $3N$-dimensional configuration space for a system with $N$ electrons of infinite complexity compared to macroscopic physics in 3D.
This means that QM is not rational physics violating reductionism with micro infinitely more complex than macro.
RealQM offers a new SE in terms of classical physics continuum mechanics in 3D thus in the form of rational physics.
RealQM is now implemented in a code allowing simulation of large molecules like proteins with 1000s of atoms, or clusters of simple molecules allowing atomic simulation of bulk properties of fluids and solids, see previous post.
RealQM is essentially a 3-line code for time-stepping (i) non-overlapping electron densities, (ii) evolution of free boundary between densities and (iii) Poisson equation for potentials, and so allows simulation of 1000 atoms on a $1000^3$ grid thus with 1TB RAM.
A $1000^3$ grid resolves 3 orders of magnitude. Macroscopic physics can be described on scales ranging over 3 orders of magnitude on a decimal scale:
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