Is cold fusion a twistronic effect?

I have a hypothesis to explain the excess heat produced in a Fleischmann-Pons reaction, that the heat is produced by a nuclear reaction, and that reaction is triggered by a twistronic effect.

In Ron Maimon’s extensive stackexchange post on Cold Fusion he lists the following theory in his section Theoretical Work:

Lattice enhancement mechanisms: This was the focus of [Julian] Schwinger and [Peter] Hagelstein, neither of whom claimed to have solved the problem. The problem with such theories is only that the effects have to be collective over thousands of atoms to explain taking eV energies into KeV energies, and it is thermodynamically difficult to imagine how you can take such entropic energy into such an entropically unfavorable place as a single particle.

Twistronics provides a structured way to obtain crystal-like effects over hundreds or thousands of atoms.

Q: What is twistronics?

Twistronics is the study of near-identical atomic and molecular structures that meet with a twist angle at a plane.

Twistronics wasn’t suggested until 2007 when “Antonio Castro Neto hypothesized that pressing two misaligned graphene sheets together might yield new electrical properties…” [from wikipedia]

Twistronics was observed in 2010 when a team at Rutgers found that two sheets of graphene stacked and twisted at a magic angle of 1.1 degrees enters a superconducting state.

Q: Why does that happen?

The theoretical explanation for the superconductivity is that “the electronic band structure exhibits flat bands near zero Fermi energy, resulting in correlated insulating states at half-filling. Upon electrostatic doping of the material away from these correlated insulating states, we observe tunable zero-resistance states with a critical temperature of up to 1.7K” [nature article 26160]

Q: What is Fleischmann-Pons?

If you really don’t know, just Google it. It’s an experiment run on a palladium crystal loaded with deuterons that produces excess heat that is theorized to be due to nuclear fussion, but this is controversial. The palladium crystal is first loaded with deuterons, probably by long, slow exposure to deuterium gas. The crystal expands while being loaded, and it is easy to crack it inadvertently. Then you run electrical current through it, and it (hopefully) produces excess heat that exceeds the input electrical energy. It’s a notoriously difficult experiment to carry out, and nobody’s really been able to make it work consistently and well.

Q: Where did you learn about it?

Peter Hagelstein’s videos – his January 2013 MIT lectures:

Q: How could twistronics explain Fleischmann-Pons?

Fleischmann-Pons might be caused by a twistronic effect triggered by a crack in the palladium crystal. Twistronics suggests to me that a crack at some critical angle, along some critical plane, would create a supersized crystalline “fundamental cell”, many atoms across and down, which would then repeat as a mega-crystalline pattern. Such a mega-crystal, subject to an electrical current (perhaps also in a critical direction, or a sine way at a critical frequency, or a square wave), might be able to generate extremely large electrical fields in a small region, much like a number of small waves can pile up to form a super-wave at sea. Such strong localized forces could induce a nuclear reaction, even at a low probability, by slamming a light deuteron into a heavy palladium nucleus.

Q: Why a D-Pd reaction, not D-D?

All known deuteron-deuteron reactions produce gamma radiation. It’s easy to detect, to the point where individual nuclear reactions can be observed using an array of scintillation detectors. No gamma radiation is observed in a Fleischmann-Pons experiment.

Q: Why not?

A: The reaction is probably not deuteron-deuteron. It’s probably deuteron-palladium, and it could be either fusion or fission. A search of the database [what db?] about ten years ago yielded no results looking for deuteron-palladium reactions, but a host of reactions for proton-palladium. Deuterons, I think, should be more reactive than protons, so probably the reason there is no published data for deuteron-palladium is simply that the experiment hasn’t been run.

Q: Is that why we see heat and no gamma radiation in a Fleischmann-Pons experiment?

Hypothesis: There’s a previously un-observed deuteron-palladium reaction producing only heat and no gamma radiation, in the D-Pd nuclear spectrum. This could be checked using a much simpler and more reliable way than Fleischmann-Pons: just accelerate a beam of deutrons at a palladium target and measure the nuclear spectrum.

Q: Why don’t the experiments work without something like 90 percent loading of the deuteron?

A: It’s a long-range effect triggered by a deuteron-palladium crystal. The ideal theoretical model would 100 percent loading – all of the gaps in the Pd crystal are filled with D nuclei, and then it’s completely regular.

Q: Is anything else needed?

A: Yes! A crack! A crack is needed in the crystal, to introduce a twistronic situation where one part of the crystal is offset to another part of the same crystal by a fixed angle in the plane of intersection between the crystals.

Q: And this is why Fleischmann-Pons is so hard?

Hypothesis: To successfully carry out a Fleischmann-Pons experiment, you need to not only form a palladium crystal and load it to at least 90 percent with deuterons, you then have to crack the crystal at just the right angle. Then you need to hit it with electrical current at just the right angle, and maybe the right frequency or waveshape, too.

Q: Can this behavior be predicted theoretically?

A: Maybe. An attempt could be made to set up some super-simplified model that might give us a valuable prediction. There’s at least one simplified model [cite?] that predicts the flat band structure of twisted graphene.

Q: Are there any theoretical alternatives to a such super-simplified model?

A: Quantum chemistry software. At least one of these programs pitches that it can handle repetitive crystal structures. An investigation is warranted to see if such a model predicts anything useful. Hopefully, the program could model every electron in the entire crystal cell, and with every nucleus. Pd’s atomic number is 46, so it’s got 46 electrons for every nucleus. This would be hundreds, probably thousands of particles. Or you could use a model where the core of the atom is treated as a single shrouded object, removing the non-valance band electrons from the picture. Would simplify it; who knows how much.

Q: What would the model look like?

It would be a repetitive 2D-lattice, say in the x-y plane, but there would be an interface plane between two crystals twisted relative to one another by a fixed angle, and the two crystals would go on infinitely in the positive and, respectively, negative z-directions.

Pd’s electron configuration is [Kr] 4d10, so each Pd nucleus would be surrounded by 36 electrons in a Kr-shell configuration, and the remaining 10 electrons would be part of a electron gas permeating the entire crystal. I need to review/learn Ashcroft and Mermin, “Solid State Physics”, especially the first fifteen chapters or so.

All Fleischmann-Pons experiments use electric current. To model this, we want to introduce an external electric field. Sinusoidal would be easiest, but we’d also like to investigate square and triangle waves. Based on published mean free path estimates for electrons in metallic solids, I’d expect hundreds of angstroms between collisions between an electron and the Pd-D matrix. From what I remember of Ashcroft and Mermin, I’d expect lots of phonon modes of excitation, and then we have a Fermi surface, and it varies depending on the angle the phonon makes with the crystal. Without reviewing Ashcroft and Mermin further, I’d model a single electron that comes in to the crystal, interacts with it, and is scattered.

Q: How could we predict the behavior of such a model?

One idea is to take an existing QM program, specialized for crystals (at least one promotes this on their wikipedia page), and see how to modify it to handle two half-infinite crystals that meet at a plane with a twist angle. Hopefully it can model electrical current through the crystal, too.

Q: And if the program works, it would predict whether or not there’s a nuclear reaction?

A: Maybe or maybe not. The quantum chemistry programs are a lot like large language models – they have millions of parameters that they’re varying to try to get a solution close to the exact one. Sometimes they do a really good job. If the software predicts a twist angle, it should be investigated in the lab to see if it’s real. If the current batch of software doesn’t predict a twist angle, I wouldn’t regard that as definitive rejection of the hypothesis. The software just isn’t accurate enough.

Q: If theory doesn’t work, how about experiment?

A: My current preferred experimental setup would form a thin film of crystalline Pd on a substrate (glass microscope slide?). Perhaps heat treat it to obtain the desired crystalline structure. Then it needs to be infused with deuterons by long duration exposure to deuterium gas. We need some way to study its crystalline structure (X-rays? electron microscope?) to make sure that it has the crystalline structure we want. We also need to know exactly how the crystalline structure is aligned relative to the substrate. We form two such slides, and bring them into contact with each other. Ideally, we’d like to cut out a circular cross section of both crystals, and obtain a thin cylinder of twisted Pd-D that can be tested by applying electrical current across it at various angles.

Q: Are you sure about all this?

Hell, no! I don’t know what’s going on! Twistonics just seems like a good guess!

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