Theoretical Physical Foundation of Chemistry?

Question posed to chatGPT (instead of living chemists and physicists, who are not eager to communicate):

• How does a chemist and a physicist cope with the fact that StdQM does not serve as a theoretical physical foundation of chemistry as the science of molecules? 

Answer by chatGPT:

Great question — and it cuts straight to a real cultural fault line between chemistry and physics.

The short version (without dodging): chemists and physicists cope very differently, and the difference is less about equations than about what they think a theoretical foundation is supposed to do.

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How chemists cope: pragmatic realism (with a straight face)

Most chemists quietly accept that StdQM does not, by itself, found chemistry as the science of molecules — and then they move on.

Here’s how that coping works in practice:

1. Instrumental success beats foundational purity

Chemists care first about:

• molecular structures,

• reaction energies and barriers,

• spectra,

• trends across compounds.

If a method delivers reliable numbers and patterns, it’s considered physically grounded enough. Whether those results are a logical consequence of the axioms of StdQM is usually secondary.

So when molecular structure, bonding, and reactivity are not derivable strictly from the Schrödinger equation, the chemist shrugs and says:

“Yes — that’s why we invented chemistry.”

2. Heuristics are treated as legitimate physics

Concepts like:

• chemical bonds,

• hybridization,

• orbitals “belonging” to atoms,

• electronegativity,

are not derived from StdQM. Chemists know this. But they treat them as effective physical concepts, not as mathematical consequences.

This is a key move:

👉 chemistry is not reduced physics; it is autonomous physics of molecules.

3. “QM constrains chemistry” is enough

Chemists often adopt the weaker claim:

StdQM constrains what chemistry can be like, even if it doesn’t construct it.

That’s how they live with the gap:

• QM supplies energy scales and stability constraints,

• chemistry supplies structure, mechanisms, and meaning.

No crisis — just division of labor.

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How physicists cope: semantic deflection and authority

Physicists cope less comfortably, because the issue threatens reductionism.

1. Redefining “foundation”

Physicists often say:

“Chemistry is founded on QM because nothing in chemistry violates QM.”

But notice the shift:

• “founded on” no longer means logically derived from

• it means not forbidden by

This is a constraint-based, not a constructive, foundation.

2. Declaring emergence without derivation

When pressed on molecular structure, bonding, or chemistry-specific laws, the answer is often:

“These are emergent phenomena.”

But in many cases:

• no derivation exists,

• no limiting procedure is known,

• no theorem connects axioms to molecules.

So “emergence” functions rhetorically, not mathematically.

3. Computational success is substituted for theory

Another coping strategy:

“Quantum chemistry works extremely well computationally.”

True — but this hides a crucial fact:

• quantum chemistry works because it adds structure, approximations, and chemical insight not contained in StdQM.

The physics is no longer “StdQM alone”; it’s StdQM + chemically motivated modeling choices.

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The unspoken truce between chemistry and physics

What actually holds the field together is an unacknowledged compromise:

• Chemists accept that their core concepts are not derivable from StdQM, but insist they are physically real.

• Physicists accept chemistry’s success, but avoid formal questions about derivability and meaning.

Both sides quietly avoid asking:

If molecules are real physical objects, what are the postulates of molecular physics?

Because once you ask that, StdQM alone is no longer sufficient.

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The honest bottom line

• StdQM is not a theoretical physical foundation of chemistry in the same way Newtonian mechanics is a foundation of elasticity.

• It is a constraint framework, not a constructive molecular theory.

• Chemistry survives — and thrives — because it implicitly operates with additional physical principles, even if they are not formally axiomatized.

Chemists cope by doing chemistry.
Physicists cope by not looking too closely.

And the fact that both strategies work is precisely why the problem remains unresolved — not because it doesn’t exist, but because science can function for a long time on productive ambiguity.

Conclusion/Summary: 

• StdQM does not serve as theoretical physical foundation of chemistry. 
• Chemists feel a need to add physics beyond StdQM but what and why is left open.
• Physicists redefine foundation to mean anything delivered by RealQM.