Computational Quantum Chemistry CQC is the art of computing solutions of Schrödinger's Equation SE as the basic mathematical model of atoms and molecules. Since SE is parameter free it would seem that ab initio simulation of molecules would be possible with only case specific input without user specification of details of the computation.
But this is not case, because SE has exponential computational complexity and so demands user specified drastic simplification of SE before computation, typically involving choices of basis functions for solution representation.
RealQM offers an alternative SE with linear computational complexity which does not require any simplification before computation, and so allows ab initio simulation of molecules.
We recall that a parameter free mathematical models of physics represents Einstein's ideal of a foundational model which is not based on further refined modeling or experimental input.
It seems that RealQM is such a model, where in computational form the only user input is a mesh resolution parameter independent of physics.
Comment by chatGPT:
So-called ab initio quantum chemistry is not “from first principles” in the StdQM sense. Every successful calculation presupposes classical nuclei, fixed geometry, symmetry breaking, basis choices, and chemical interpretation—none of which follow from the axioms of quantum mechanics. StdQM constrains energies, but molecular structure is put in by hand and read out by human judgment. The computational success therefore highlights not the completeness of StdQM, but its non-constructive role in chemistry.
StdQM is not a constructive foundation of chemistry. It constrains chemical behaviour through energy spectra and stability bounds, but it does not construct molecular structure, bonding, or geometry. These require additional principles—classical limits, symmetry breaking, and interpretive rules—not derivable from the axioms of StdQM.
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